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chasing an electrical draw
#907302
01/17/11 03:24 PM
01/17/11 03:24 PM
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California
mickm
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i have a smallish draw when the car is off that drains the battery after two weeks or so.
in starting to chase it, i disconnected the clock, which should be the only thing drawing current when the car is off. with a multimeter connected to the negative side of the battery, i was still drawing almost 12 volts, 11.8 or so.
i started popping fuses, and the only one that made a difference was the third from the right, (forget which one that is, have it written down in the garage), where the voltage dropped to ~8.9V. that was the only difference i could find by pulling fuses.
so my first question is even if there is nothing actually causing a draw, will there still be nominal voltage in the system? kind of like a battery that doesn't have enough charge to be useful still has a voltage?
the second question is if that is the case, now that i know which circuit it is on, do i just start following the circuit and disconnecting things, same idea as pulling the fuses?
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Re: chasing an electrical draw
[Re: 70SportSatellite]
#907304
01/17/11 03:48 PM
01/17/11 03:48 PM
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Joined: Jan 2008
Posts: 299
East Brunswick, NJ
finadk
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Use the test light method described. But i would not pull the fuse for the door light circuit that constantly on circuit is most likely the circuit with the problem. Is there an alarm or sound system amp in the car? Check the easy stuff first trunk light dome light, glove box light staying on?,
Scott
Scott
1956 Dodge Custom Royal Lancer (408 Stroker, 4 Wheel Disc Brakes, Rack & Pinion, 6 speed)
2002 Dodge Ram 1500 Quad Cab
1976 Corvette
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Re: chasing an electrical draw
[Re: 70SportSatellite]
#907305
01/17/11 03:50 PM
01/17/11 03:50 PM
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Montana
Yancy Derringer
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You may be using the wrong technique, that is, "volts." As said above START with a test lamp. Depending on how big the test lamp is ---how much current it draws-- will determine the "draw" you can find with it.
That is, a test lamp using a huge bulb such as a stop or tail lamp will only "show color" on a fairly large "draw."
A tiny small bulb, or a 12V LED, will find smaller "draws."
After you have found the draw with your lamp, and it is now "dark"--------
THEN get out your meter, --BUT THIS DEPENDS--
You need to be sure to set your meter up for maximum AMPERAGE, NOT VOLTAGE.
On most meters, this should be 10 or 20 amps. BE CAREFUL, there are several pitfalls.
Some meters are fused in the amperage mode, some are not
DO NOT put your amperage selected meter TO GROUND. Current (ammeters) ALWAYS go in series, BUT---
If you screw up and cause a high current draw, like try and turn the key to "start" when the meter is hooked up---you will either destroy the meter, or blow it's fuse IF it is protected.
THEN after you have found the "draw" and the meter no longer shows anything on the heavy 10-20 amp scale, then set the meter down for more sensitive milliamp scales, but AGAIN be careful not to cause damage. On some meters (My Flukes) there are separate meter jacks which must be used for current scales.
THAT IS WHY you use the lamp test first---because a 12V lamp CAN NOT be damaged by your automotive system.
You started out right by removing the fuses. Don't discount anything in the car. I have found "draws" that were basically caused by corrosion, that is, a damaged harness under the doorsill that was full of corrosion. I also found a draw once that was caused by "junk" in the bottom of the cigarette lighter
The point? It's not always an object like the radio, or the "map light," etc. I can be something "in between."
ALSO be sure you unhook the alternator and check it for "draw." One or more diodes in the alternator may become what is called "leaky". These can draw anywhere from a tiny amount, to enough to cause problems.
HERE IS PART OF why you cannot check with a voltmeter "in series:"
EVEN DIRT on top of the battery will show "some voltage" on modern digital meters, or even sensitive analog type meters. This is because the combination of boiled acid, dirt, condensed humidity, etc, causes a conductive film, and the meter you are using does not draw very much current---in the millionth's of amps, or microamp range.
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Re: chasing an electrical draw
[Re: 70SportSatellite]
#907306
01/17/11 03:51 PM
01/17/11 03:51 PM
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mickm
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Quote:
Take a test light and hook it up in-line on the positive terminal of the battery. In other words, the clip to the battery and the probe touching the cable end. it should work the other way around but that's I how I normally do it.
The current draw in a normal situation should be so small it should not light the bulb. If the bulb lights then there is an excessive draw. If it does not light turn on the headlights. itr should now be very bright. If it doesn't, check your connections, it should.
Now, turn off everything and if the bulb glows start pulling fuses. When you find the fuse that turns the light out determine what it runs and start disconnecting those items.
Since you will have the door open be sure to depress the door jamb switch or pull the fuse for it, otherwise you will chase your tail.
sounds like a good plan. so the volt meter shows voltage, which isn't really what i'm looking for, i'm looking for current, which is exposed by there being enough current to light the light, correct?
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Re: chasing an electrical draw
[Re: finadk]
#907307
01/17/11 03:53 PM
01/17/11 03:53 PM
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Montana
Yancy Derringer
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Quote:
Use the test light method described. But i would not pull the fuse for the door light circuit that constantly on circuit is most likely the circuit with the problem. Is there an alarm or sound system amp in the car? Check the easy stuff first trunk light dome light, glove box light staying on?,
Scott
ALSO in addition to above, DISCONNECT your sound system. This is because of two things. Many sound systems have circuits that are "always on." As with alternators, there are components that can be or become "leaky."
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Re: chasing an electrical draw
[Re: Yancy Derringer]
#907308
01/17/11 03:58 PM
01/17/11 03:58 PM
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California
mickm
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Quote:
You may be using the wrong technique, that is, "volts." As said above START with a test lamp. Depending on how big the test lamp is ---how much current it draws-- will determine the "draw" you can find with it.
That is, a test lamp using a huge bulb such as a stop or tail lamp will only "show color" on a fairly large "draw."
A tiny small bulb, or a 12V LED, will find smaller "draws."
yup, this makes sense.
Quote:
Some meters are fused in the amperage mode, some are not
DO NOT put your amperage selected meter TO GROUND. Current (ammeters) ALWAYS go in series, BUT---
my meter is fused. can you explain this, what do you mean "put your amperage selected meter TO GROUND"? so i want to
1) check that the current i'm chasing is within the range of what my meter will handle,
2) make sure i don't introduce more current than that, and
3) the meter needs to be hooked up in series, the same way the bulb was, correct?
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Re: chasing an electrical draw
[Re: finadk]
#907309
01/17/11 04:00 PM
01/17/11 04:00 PM
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mickm
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Quote:
Use the test light method described. But i would not pull the fuse for the door light circuit that constantly on circuit is most likely the circuit with the problem. Is there an alarm or sound system amp in the car? Check the easy stuff first trunk light dome light, glove box light staying on?,
Scott
no, none of that in the car, but i haven't yet checked for the simple stuff. nothing is obvious anyway.
hmmm... i just remembered. it has been a while, but the cigarette lighter doesn't pop up on it's own when hot, and blows the fuse. i have used the lighter to power my LM-1, so i know it is good, but maybe as mentioned in another post there is some junk down in there.
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Re: chasing an electrical draw
[Re: mickm]
#907310
01/17/11 04:05 PM
01/17/11 04:05 PM
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Montana
Yancy Derringer
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Quote:
my meter is fused. can you explain this, what do you mean "--EDIT DO NOT EDIT--put your amperage selected meter TO GROUND"? so i want to
1) check that the current i'm chasing is within the range of what my meter will handle,
2) make sure i don't introduce more current than that, and
3) the meter needs to be hooked up in series, the same way the bulb was, correct?
Right. Even fused meters CAN be easily destroyed. Some meters are fused for scales EXCEPT the "high amp" scales, still others are not fused at all in current scales.
So you have it right. I do not know what your knowledge/ experience is, just trying to be sure you don't blow up your meter. Even I have popped the rather expensive special fuse in my Fluke a "couple of times" here and there.
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Re: chasing an electrical draw
[Re: Andrewh]
#907312
01/17/11 04:12 PM
01/17/11 04:12 PM
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mickm
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Quote:
yes amps are what you are looking for not voltage.
Can't tell if you are trouble shooting an old car or new.
the 70 RR in my sig.
Quote:
Also there is an amperage shunt technique that allows you to put a resister inline with your meter so you don't blow it up and then multiply by 10 or something to get the actual amperage draw.
I have it in a motor magazine somewhere, but can't find it at the moment. Might be a good artical on line about it if you do a search.
for an old car a month before dead would be good. 2 weeks for an old car is bad.
for a new car, 2 weeks isn't so bad, but would be pushing it.
i have been disconnecting the battery, but would like to not have to do that every time. and would also like to not have to get up at 3am when it hits me and i can't remember if i disconnected it or not 
but even a month seems like a short amount of time. i hear plenty of people say their car sits for longer than that, and plenty of juice in the battery.
but yes, i do need to chase it down.
post that info from the article if you find it.
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Re: chasing an electrical draw
[Re: mickm]
#907313
01/17/11 04:23 PM
01/17/11 04:23 PM
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Joined: Jan 2003
Posts: 28,071
Irving, TX
feets
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Forget voltage. That's not what you want to look for. You need amperage.
When wiring trailer lights I've had 12 volts at the light but not enough current to blow a 3 amp fuse.
The test light will not glow unless there's sufficient amperage.
The battery can have a 12 volt draw for a month and be fine if the draw isn't pulling appreciable amperage.
The test light is also easier to mess with. Prop it up so you can see it from the driver's seat and start yanking fuses.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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Re: chasing an electrical draw
[Re: mickm]
#907314
01/17/11 04:28 PM
01/17/11 04:28 PM
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Joined: Aug 2005
Posts: 11,543
chicagoland,usa
buildanother
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The simple test light between batt post and batt term works great on old cars such as yours. Normally with doors shut, you can connect test light between post and cable terminal, the light should not light. Then if you open car door, the test light should light brightly. If you have a newer radio with memory, and a clock etc, it may light the light and then it should fade out, or almost out. That is not really a big enough draw to kill a good battery in only 2 months. 
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Re: chasing an electrical draw
[Re: Andrewh]
#907316
01/17/11 08:01 PM
01/17/11 08:01 PM
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Montana
Yancy Derringer
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Quote:
found it.
here is the jist.
wire a 1.0 ohm 10 watt resistor in series with the negitive cable.
so one end of the resistor on the battery, one end on the negitive cable.
Take a volt meter and measure VOLTAGE across the resistor.
According to the article, due to ohms law, the actual voltage measures will be equal to the amps being drawn through the resistor.
that way you don't risk your volt meter in amp mode.
I don't know what happens if the amps are higher than 12, since I didn't do the math. I don't know if it is possible to read a higher than 12 amp draw since you are limited by the battery's potential.
Ohm's basic law is I = E / R which means
AMPS = VOLTAGE divided by OHMS
So if the resistor (1 ohm) is put DIRECTLY across a 12V battery (as in a heavy short in the system, you get
AMPS = 12 / 1
So the 1 ohm resistor can draw a maximum current of 12 amps
However, WATTAGE is P = IE, which means
WATTS = AMPS X Volts
So your resistor is dissipating 12 amps X 12 volts or
144 WATTS!!! That little resistor won't last long if you were to have a heavy short in the harness
However, 10 watt resistors don't cost much, and are cheaper than damaging a meter!!
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Re: chasing an electrical draw
[Re: JonC]
#907318
01/18/11 12:13 AM
01/18/11 12:13 AM
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mickm
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Quote:
Do you have an aftermarket radio that may draw current all the time?
stock am radio. and what a joy it is to listen to!
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Re: chasing an electrical draw
[Re: Andrewh]
#907319
01/18/11 12:16 AM
01/18/11 12:16 AM
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mickm
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Quote:
found it.
here is the jist.
wire a 1.0 ohm 10 watt resistor in series with the negitive cable.
so one end of the resistor on the battery, one end on the negitive cable.
Take a volt meter and measure VOLTAGE across the resistor.
According to the article, due to ohms law, the actual voltage measures will be equal to the amps being drawn through the resistor.
that way you don't risk your volt meter in amp mode.
I don't know what happens if the amps are higher than 12, since I didn't do the math. I don't know if it is possible to read a higher than 12 amp draw since you are limited by the battery's potential.
nice, i'll do that if i need to. first thing is to look at the one circuit that dropped when i popped the fuse.
one question not answered yet though...
if there is no draw at all, will i still see voltage in the circuit? i had ~12v with the one fuse in, but only ~9v with the fuse out?
i know i need to be looking at amps, but i am curious about this.
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Re: chasing an electrical draw
[Re: mickm]
#907320
01/18/11 12:26 AM
01/18/11 12:26 AM
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Joined: Jun 2008
Posts: 1,822
Colorado
denfireguy
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Quote:
Quote:
found it.
here is the jist.
wire a 1.0 ohm 10 watt resistor in series with the negitive cable.
so one end of the resistor on the battery, one end on the negitive cable.
Take a volt meter and measure VOLTAGE across the resistor.
According to the article, due to ohms law, the actual voltage measures will be equal to the amps being drawn through the resistor.
that way you don't risk your volt meter in amp mode.
I don't know what happens if the amps are higher than 12, since I didn't do the math. I don't know if it is possible to read a higher than 12 amp draw since you are limited by the battery's potential.
nice, i'll do that if i need to. first thing is to look at the one circuit that dropped when i popped the fuse.
one question not answered yet though...
if there is no draw at all, will i still see voltage in the circuit? i had ~12v with the one fuse in, but only ~9v with the fuse out?
i know i need to be looking at amps, but i am curious about this.
Yes you will see voltage. Again, it is current flow that depletes a battery. Voltage is the potential to supply energy, current flow is the energy. It is like my kid, he has the potential to do work but until I actually see it, it is only potential and no work is done.
Craig
2014 Ram 1500 Laramie, 73 Cuda
Previous mopars: 62 Valiant, 65 Fury III, 68 Fury III, 72 Satellite, 74 Satellite, 89 Acclaim, 98 Caravan, 2003 Durango
Only previous Non-Mopar: Schwinn Tornado
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Re: chasing an electrical draw
[Re: denfireguy]
#907321
01/18/11 02:03 AM
01/18/11 02:03 AM
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Joined: Nov 2009
Posts: 2,177
ill
dennismopar73
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look at the alternator might have a diode out causing it to 'back up ' thru the system? , as on another post check you re radiator maybe it discharging hahahhaha l o l 
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Re: chasing an electrical draw
[Re: dennismopar73]
#907322
01/18/11 03:50 AM
01/18/11 03:50 AM
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mickm
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Quote:
look at the alternator might have a diode
out causing it to 'back up '
thru the system?
, as on another post check you re radiator
maybe it discharging hahahhaha
l o l
i did. it was putting out 110v, so i plugged in the toaster oven and made a sandwhich for lunch
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Re: chasing an electrical draw
[Re: dennismopar73]
#907323
02/05/11 08:52 PM
02/05/11 08:52 PM
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mickm
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so using a test light, i have isolated this to the circuit that is the emergency flashers and accessories.
going by the wiring diagram, this is where i'm at:
- there is no glove box light on this car.
- time delay relay, see below
- clock is unplugged, draw is still there
- map lamp switch unplugged, draw still there
- and the emergency flasher, which i couldn't find.
so 2 items i don't have, 2 out of the 5 don't make a difference when unplugged.
can someone give me a hint as to where the emergency flasher is?
i think i don't have a time delay, as there is a loose connector under the dash that matches the same configuration as shown in the diagram, and the time delay seems to simply go to the ignition switch lamp, and there is nothing connected to that. i also can't find anything in the vicinity of that connector that matches it.
i did unplug the connector coming from the steering column, thinking that maybe there was something funky with the emergency flasher switch there, and the light was still on.
so at this point, as near as i can tell, it either has to be the emergency flasher, or some small short somewhere after the fuse box.
any thoughts?
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Re: chasing an electrical draw
[Re: superbeedave]
#907325
02/05/11 09:17 PM
02/05/11 09:17 PM
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mickm
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Quote:
Lets see if i can help you with finding the emergency flasher. There is a cover down below that covers the steering column. If you remove
that cover it will likely be to the left or right tucked behind
the panel clipped in a "U" like clip. That is where it is on my 69 Bee. But don't quote me on that!
thanks for the tip, but that wasn't it. i had the brilliant idea of turning the signals on, and traced it down by the sound! it sits next to the ash tray, in a slide in clip kind of thing.
but, that wasn't it. unplugged it, and the test light is still lit.
so, unless i screwed up somehow, it seems that i have eliminated everything on the circuit, and i still have the draw.
where do i go from here?
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Re: chasing an electrical draw
[Re: superbeedave]
#907328
02/05/11 11:38 PM
02/05/11 11:38 PM
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mickm
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i don't think it is the ignition switch, i disconnected the whole ignition connector to eliminate something at the emergency flasher switch. i isolated it to that circuit by pulling fuses one by one, and the draw went away only when this one fuse is pulled, so it has to be somewhere along the circuit. i'm thinking some kind of short, pinched wire or something. but keep throwing ideas out, doesn't mean i haven't overlooked something 
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Re: chasing an electrical draw
[Re: stumpy]
#907331
02/06/11 01:57 AM
02/06/11 01:57 AM
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mickm
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Quote:
You do have the dome light switch on the door taped down or shut off somehow don't you.
yes, i just have the door shut while i'm inside. the test light glows when it's just the draw, it shines bright when i open the door. noticeable difference.
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Re: chasing an electrical draw
[Re: Andrewh]
#907332
02/06/11 02:00 AM
02/06/11 02:00 AM
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mickm
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Quote:
if I read it right, it also goes to the headlight switch?
also a headlight relay on the other side.
so you pull that fuse and the light goes out?
did you try the trick to figure out amps?
may have missed that, i didn't see that it goes to the headlight switch, i'll look again.
yes, pull the fuse, and the test light connected between the (disconnected) negative battery cable and the negative post goes out.
what trick about amps? may have missed that in an earlier post.
i know it's a small but reasonable draw, because if i leave the battery connected, it will be drained in about two weeks.
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Re: chasing an electrical draw
[Re: Andrewh]
#907334
02/06/11 01:50 PM
02/06/11 01:50 PM
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mickm
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Quote:
wire a 1.0 ohm 10 watt resistor in series with the negitive cable.
so one end of the resistor on the battery, one end on the negitive cable.
this?
to protect the multi-meter...
i'm not even using it at this point, just a simple test light.
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Re: chasing an electrical draw
[Re: mickm]
#907335
02/06/11 02:45 PM
02/06/11 02:45 PM
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Yancy Derringer
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If I read this right, you have GOT to figure out how to split the wiring. Frankly, I doubt it's in the emergency flasher stuff, but some of the wiring is related
The way I read, the conductor comes off the fuse box ---D31-18BK-- AND FEEDS one terminal if the emergency flasher connector. THAT SAME terminal splits off with D3-19P which feeds one side of the stop lamp. THAT TERMINAL splits the wire off M1-18P to a 3 wire connector labled "to dome lamp wiring (body.) That connector should be over near the left underdash, maybe in the kick panel. It is the first thing I'd pull, the second thing is the headlight connector.
Get into the kick panels and sill plate, and examine for corrosion and moisture under there. Pull the dome light switches or at least the wiring off.
I would get rid of the "key in" buzzer "just because."
the shop manual is vague. It pictures the standard flasher up in the dash ? to the left? of the lighter, I don't see the emergency.
If you can wire up enough stuff to get the emergency to flash, that's the best way to find it.---listen for it. Shop manual is referring to removing fuse panel and dropping out of way, so I'd think emerg. flash is back in there by/ behind the glove box
Still another manual reference says it's on the lower panel to the right of the steering column.
I would think the time delay relay/ column light could be a real suspect, but I guess you've disconnected the column?
Time for a simple easy follow list:
What fuse/ fuses drops the problem?
What have you disconnected, harness, etc, that does or does not drop the problem?
You don't have a console?
This should NOT be that difficult to find. Stick with us.
'S been 30 years since I was under a 69/ 70 Roadrunner.
Last edited by Yancy Derringer; 02/06/11 03:12 PM.
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Re: chasing an electrical draw
[Re: mickm]
#907336
02/06/11 03:46 PM
02/06/11 03:46 PM
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Andrewh
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Quote:
Quote:
wire a 1.0 ohm 10 watt resistor in series with the negitive cable.
so one end of the resistor on the battery, one end on the negitive cable.
this?
to protect the multi-meter...
i'm not even using it at this point, just a simple test light.
The problem is there can always be potiential to draw voltage. so the light will come on.
you may be chasing a normal draw. Until you check to see how much current you are pulling you have no idea.
the fact your door switches make it burn brighter tells me you are not drawing much current right now.
no point in wasting time if it is less than .4 amps. But till you run an amp check, you have no idea and could just be wasting time.
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Re: chasing an electrical draw
[Re: Andrewh]
#907337
02/06/11 08:44 PM
02/06/11 08:44 PM
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Yancy Derringer
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Quote:
The problem is there can always be potiential to draw voltage. so the light will come on.
you may be chasing a normal draw. Until you check to see how much current you are pulling you have no idea.
the fact your door switches make it burn brighter tells me you are not drawing much current right now.
no point in wasting time if it is less than .4 amps. But till you run an amp check, you have no idea and could just be wasting time.
THIS IS NOT TRUE AND MAKES NO SENSE
FIRST, there is NOT "always the potential to draw voltage" (so the light will come on.)
IF the system is "clean" that is, HAS no parasitic draw, the lamp will not light, PERIOD.
I'm speaking here using the "typical" parts store 12V test lamp, which typically uses something like a no57, or a cartridge type lamp
If it uses an LED or some other tiny "wheat" bulb, you may have a point
Quote:
you may be chasing a normal draw. Until you check to see how much current you are pulling you have no idea.
Once again, a "decent" 12v test lamp, like a 194 or 57, etc, SHOULD NOT LIGHT if things are normal. There is no such thing as a "normal draw" that will light a lamp -- in these old cars
Quote:
the fact your door switches make it burn brighter tells me you are not drawing much current right now.
This statement depends somewhat on how much current the test lamp itself draws. It could be very little, could be a lot.
Quote:
no point in wasting time if it is less than .4 amps.
This is about the silliest thing I've ever read. .4, ALMOST 1/2 AN AMP is a HUGE load for a car that may be parked for long periods of time. Let's say you have a 100 amp hour rated battery. Negating the "20 hour" rating, and just using straight math, this means that a 100 amp-hour battery WOULD ONLY LAST 200 hours!!! (100/ .5) THAT IS ONLY AROUND 8 DAYS!!!!
To put this into simple terms, IF YOU HAVE A PARASITIC DRAW OF .4 AMPS, IT'S WAY TOO MUCH!!!
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Re: chasing an electrical draw
[Re: Yancy Derringer]
#907338
02/06/11 11:45 PM
02/06/11 11:45 PM
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Joined: Feb 2003
Posts: 8,714
Andrewh
master
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master
Joined: Feb 2003
Posts: 8,714
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Quote:
Quote:
The problem is there can always be potiential to draw voltage. so the light will come on.
you may be chasing a normal draw. Until you check to see how much current you are pulling you have no idea.
the fact your door switches make it burn brighter tells me you are not drawing much current right now.
no point in wasting time if it is less than .4 amps. But till you run an amp check, you have no idea and could just be wasting time.
THIS IS NOT TRUE AND MAKES NO SENSE
FIRST, there is NOT "always the potential to draw voltage" (so the light will come on.)
IF the system is "clean" that is, HAS no parasitic draw, the lamp will not light, PERIOD.
I'm speaking here using the "typical" parts store 12V test lamp, which typically uses something like a no57, or a cartridge type lamp
If it uses an LED or some other tiny "wheat" bulb, you may have a point
Quote:
you may be chasing a normal draw. Until you check to see how much current you are pulling you have no idea.
Once again, a "decent" 12v test lamp, like a 194 or 57, etc, SHOULD NOT LIGHT if things are normal. There is no such thing as a "normal draw" that will light a lamp -- in these old cars
I miss spoke, my point was what if this is a normal draw, not a short. I disagree that there are no draws even in old cars, that are considered normal.
Quote:
the fact your door switches make it burn brighter tells me you are not drawing much current right now.
This statement depends somewhat on how much current the test lamp itself draws. It could be very little, could be a lot.
Quote:
no point in wasting time if it is less than .4 amps.
This is about the silliest thing I've ever read. .4, ALMOST 1/2 AN AMP is a HUGE load for a car that may be parked for long periods of time. Let's say you have a 100 amp hour rated battery. Negating the "20 hour" rating, and just using straight math, this means that a 100 amp-hour battery WOULD ONLY LAST 200 hours!!! (100/ .5) THAT IS ONLY AROUND 8 DAYS!!!!
To put this into simple terms, IF YOU HAVE A PARASITIC DRAW OF .4 AMPS, IT'S WAY TOO MUCH!!!
my mistake, not sure where I got that number from, it was the number I remember, but might be .04. regardless, that number doesn't really work either. I expect my new car to sit 2 to 3 weeks with its normal draw before killing the battery to the point where I cannot start. Assuming a 50 amp hour battery, I would expect a draw of less than .14 ish, so I guess around .1 would cover me for 2 weeks and still leave enough to start.
Again, my point is, figure out how much draw you actually have before wasting time chasing it down.
IF it is not significant, then it isn't your problem.
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Re: chasing an electrical draw
[Re: Andrewh]
#907340
02/07/11 01:09 AM
02/07/11 01:09 AM
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Joined: Jul 2006
Posts: 4,179
California
mickm
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Joined: Jul 2006
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California
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i know this draw is significant. 1) when i pull the emergency flasher fuse, the test light goes out. 2) pull any other fuse, the light stays on, so it is in that circuit. 3) leave the cable connected and the battery is dead within 2 weeks. 4) disconnect the battery cable and no problems after many weeks of sitting. it will be next weekend before i will have the time to get to it again, so i will go at it then. yancy: - emergency flasher-accessories fuse is the issue - so far, i have disconnected 1) the map light in the dash 2) the emergency flashers, (i did find it by turning on the flashers and listening for it) 3) the clock light 4) the glove box light is on this circuit, but my car doesn't have one. 5) the time delay is also on this circuit, but also doesn't have one. 6) the ignition connector from the steering column with all that disconnected, the light has stayed on. nothing so far has shut the light off. there is no console. i'll follow through with the things on your list next weekend, and report back. thanks for all the time and tips 
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Re: chasing an electrical draw
[Re: Andrewh]
#907342
02/07/11 01:38 AM
02/07/11 01:38 AM
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Joined: Oct 2010
Posts: 606
Montana
Yancy Derringer
mopar
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mopar
Joined: Oct 2010
Posts: 606
Montana
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Quote:
Quote:
Quote:
The problem is there can always be potiential to draw voltage. so the light will come on.
you may be chasing a normal draw. Until you check to see how much current you are pulling you have no idea.
the fact your door switches make it burn brighter tells me you are not drawing much current right now.
no point in wasting time if it is less than .4 amps. But till you run an amp check, you have no idea and could just be wasting time.
THIS IS NOT TRUE AND MAKES NO SENSE
FIRST, there is NOT "always the potential to draw voltage" (so the light will come on.)
IF the system is "clean" that is, HAS no parasitic draw, the lamp will not light, PERIOD.
I'm speaking here using the "typical" parts store 12V test lamp, which typically uses something like a no57, or a cartridge type lamp
If it uses an LED or some other tiny "wheat" bulb, you may have a point
Quote:
you may be chasing a normal draw. Until you check to see how much current you are pulling you have no idea.
Once again, a "decent" 12v test lamp, like a 194 or 57, etc, SHOULD NOT LIGHT if things are normal. There is no such thing as a "normal draw" that will light a lamp -- in these old cars
I miss spoke, my point was what if this is a normal draw, not a short. I disagree that there are no draws even in old cars, that are considered normal.
Quote:
the fact your door switches make it burn brighter tells me you are not drawing much current right now.
This statement depends somewhat on how much current the test lamp itself draws. It could be very little, could be a lot.
Quote:
no point in wasting time if it is less than .4 amps.
This is about the silliest thing I've ever read. .4, ALMOST 1/2 AN AMP is a HUGE load for a car that may be parked for long periods of time. Let's say you have a 100 amp hour rated battery. Negating the "20 hour" rating, and just using straight math, this means that a 100 amp-hour battery WOULD ONLY LAST 200 hours!!! (100/ .5) THAT IS ONLY AROUND 8 DAYS!!!!
To put this into simple terms, IF YOU HAVE A PARASITIC DRAW OF .4 AMPS, IT'S WAY TOO MUCH!!!
my mistake, not sure where I got that number from, it was the number I remember, but might be .04. regardless, that number doesn't really work either. I expect my new car to sit 2 to 3 weeks with its normal draw before killing the battery to the point where I cannot start. Assuming a 50 amp hour battery, I would expect a draw of less than .14 ish, so I guess around .1 would cover me for 2 weeks and still leave enough to start.
Again, my point is, figure out how much draw you actually have before wasting time chasing it down.
IF it is not significant, then it isn't your problem.
Fair enough, but your "mistake" DOES raise some interesting points:
In this day and age of "Chinese" stuff, you need to make sure your test lamp uses a good, heavy bulb, instead of some puny "wheat" bulb or an LED drawing very little current.
(I actually use a tail/ stop/turn bulb for some troubleshooting, because sometimes you WANT to "load" a test. Also, one of these bulbs rigged into a dual contact socket is very handy for stuff like charging lightweight motorcycle, etc batteries, with oversized chargers)
You do need to follow up with an ammeter/ milliameter to see just what the draw IS in current.
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Re: chasing an electrical draw
[Re: Yancy Derringer]
#907345
02/07/11 01:21 PM
02/07/11 01:21 PM
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Joined: Jul 2006
Posts: 4,179
California
mickm
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Quote:
I would find a place to isolate the dome light wiring. The connector I mentioned in the previous post SHOULD be 3? terminal, and may be down coming out of the dash group near the left side, may be near the left kick. In other words it "divides" the dome light harness through the rest of the car from the fuse circuit.
I would suspect something like wet--corrosion --rust in, something like a door like switch, or deteriorated wiring harness "down wet" such as under the door sill(s)
I dont' remember if this harness extends into the trunk (trunk light) or not.
I wish to heck I could afford to travel. I'd love to help some of you guys with this stuff.
The problem is it's been so long since I've owned a 70 that I've fogotten a lot of details, nowdays.
i'd love the help! not even the greateer experience, but sometimes just a second pair of eyes.
i will have to double check, but i'm pretty sure that the dome light does not come off of this circuit. IIRC it is the following:
- emergency indicators
- glove box light
- delay timer
- clock light (maybe clock power?)
- and map light under the dash
from there, it seems that all of this circuit should be contained underneath the dash, but i'll check again.
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Re: chasing an electrical draw
[Re: Moparteacher]
#907346
02/08/11 01:22 PM
02/08/11 01:22 PM
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Joined: Jul 2006
Posts: 4,179
California
mickm
OP
master
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OP
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Joined: Jul 2006
Posts: 4,179
California
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Quote:
The maximum acceptable draw for most manufacturers (industry standard) is 50mA. or .05Amps. Most late model vehicles draw between 10mA and 30mA. Your Roadrunner shouldn't draw much more than 10mA. We teach that anything greater than 50mA is too much!
since i know the draw is relatively small, i'll hook up my multi meter and see exactly what it is.
Quote:
Why is your LM1 wired into your cigerette lighter? Cig lighters are usually not switched through the ignition; they're always hot. This means your LM1 is always powered up.
it isn't. it's the portable meter, and when i'm using it i plug it into the cigarette lighter.
Quote:
Does the runner have power windows, locks, or seats? I've seen faulty lock and window switches cause a draw. The centering spring breaks and the switch will rest to one side. I've seen the same with the dome switch also. The switch is worn and metal spreads across the contacts just enough to close the circuit through the lamp but not enough to light the lamp.
good luck
no power windows.
again, i have to double check, but spent a few hours last weekend with it, so i'm pretty sure that the dome light is not on this circuit, but i might have missed it.
will see where this goes this coming weekend.
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Re: chasing an electrical draw
[Re: mickm]
#907347
02/08/11 02:38 PM
02/08/11 02:38 PM
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Joined: Oct 2010
Posts: 606
Montana
Yancy Derringer
mopar
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mopar
Joined: Oct 2010
Posts: 606
Montana
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If you have the original shop manual, Fig 30 "Instrument Panel Accessory Wiring Diagram--Belvedere
Shows coming off that fuse:
M5A 18P glove box lamp
M5 18P map light switch
X21 18GY clock
X1a 18P time delay relay
THEN GO TO
Fig 29, "Instrument Panel Wiring Diagram" Belvedere
shows coming off the fuse
"Emergency Flasher D31 18BK
which goes to the flasher, and a splice comes off --to--
D3-18P goes to stop lamp switch, with splice comes off --to--
M1-18P goes to far right of page a two pin connector labled
"To Dome light wiring (body)"
So one wire going to that connector is the M1-18P, 12V power to the dome circuit
The second wire in the connector is yellow, goes to door switch and headlight switch, provides ground leg switching for dome light.
THEN GO TO FIG 9
This connector seems to be shown on Fig 9 "Instrument Panel Main Harness Hook-up Belvedere
Down at bottom driver's side, shows connector with yellow and pink, down by "to headlight delay relay wiring" at bottom of page.
If you don't have these, I can photo them and post 'em.
Last edited by Yancy Derringer; 02/08/11 02:47 PM.
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Re: chasing an electrical draw
[Re: Yancy Derringer]
#907348
02/08/11 05:56 PM
02/08/11 05:56 PM
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Joined: Jul 2006
Posts: 4,179
California
mickm
OP
master
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OP
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Joined: Jul 2006
Posts: 4,179
California
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Quote:
"Emergency Flasher D31 18BK
which goes to the flasher, and a splice comes off --to--
If you don't have these, I can photo them and post 'em.
i missed that splice. i do have the FSM, so i'll continue tracking this down now that i know that.
thanks
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Re: chasing an electrical draw
[Re: mickm]
#907349
02/11/11 11:09 PM
02/11/11 11:09 PM
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Joined: Jul 2006
Posts: 4,179
California
mickm
OP
master
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OP
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Joined: Jul 2006
Posts: 4,179
California
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ok, so i found it, and it was right in front of me.
i have a repop tic-toc-tac, and it has 3 connections. 1 is power for the clock, 1 is power for the tach, and one is input signal for the tach.
with all of them connected, the draw is 79mA. since both the tach and the clock draw, and i wasn't disconnecting the feed to the tach last time, i still saw the light lit up, and thought that wasn't it.
just the clock connected is drawing ~3.5mA. the power to the tach is drawing the rest.
the thing is, the wiring diagram shows the power to the tach coming off of a different fuse, so it might be switched by the ignition. i'm not sure why it is getting power from this circuit, i'll have to trace it down.
so say 80mA on average. at 100 hours, that would draw 8 amp hours from the battery. 1000 hours would draw 80 amp hours, and 1000 hours is 41 days. this seemed to be going dead after 2 weeks or so, 14 days. 336 hours should only be a draw of 27 amp hours or so, if i have all my math right, (which i probably don't).
so someone posted that 50mA is the limit. i will call the guy i got the tach from and ask him about this, but that doesn't seem that bad.
don't these batteries have a couple hundred cranking amp hours?
so at least i've found it, looks like the thing to make sure that the power to the tach is either on the right circuit or get it on the right circuit.
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Re: chasing an electrical draw
[Re: mickm]
#907350
02/12/11 02:47 AM
02/12/11 02:47 AM
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Joined: Oct 2010
Posts: 606
Montana
Yancy Derringer
mopar
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mopar
Joined: Oct 2010
Posts: 606
Montana
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Quote:
the draw is 79mA.
!! GREAT !! So I assume you've re-checked, what's the complete system draw now that it's disconnected.
79 mills doesn't sound like much, but it adds up.
If you figure a 31 day month (car is parked for a month)
That's 31 days x 24 hours a day x .079 amps
That's a grand total of nearly 59 amp hours!!!
That's DEFINATELY enough to set a 100 AH battery on it's a$$!!!
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Re: chasing an electrical draw
[Re: Yancy Derringer]
#907351
02/12/11 03:41 AM
02/12/11 03:41 AM
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Joined: Jul 2006
Posts: 4,179
California
mickm
OP
master
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OP
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Joined: Jul 2006
Posts: 4,179
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Quote:
Quote:
the draw is 79mA.
!! GREAT !! So I assume you've re-checked, what's the complete system draw now that it's disconnected.
That's a grand total of nearly 59 amp hours!!!
That's DEFINATELY enough to set a 100 AH battery on it's a$$!!!
with it disconnected, the draw is 0. mili amps anyway, might be some micro amps. but the clock is 3.5mA, so even that would add up over time.
now i just have to figure out what to do about it.
thanks for the help!
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. I'd just keep on unplugging connectors until you stop the draw then zero in on where on that particular circuit something is improperly energized/grounded.
