battery draining. Can't find the draw

Working on a 78 Chrysler LeBaron. It's a low mileage car, absolutely stock and untouched, other than it has had an electronic ignition conversion to eliminate the Lean burn system.
So the issue is:
The battery will go dead in a day or so.

Brand new battery.

With the key off, doors and trunk closed, and checked to make sure no lights are on.
I pulled off the negative cable, and put a test light between the negative battery post, and the negative cable. The test light is bright.
I then pulled every fuse out one by one, and no change. Test light still on.
Disconnected various items such as alternator, electronic control box, wiper motor, power seat, and still no change.
Anyone have an idea as to what is drawing power?

Years ago I had a similar issue. Turns out I put new trunk weatherstripping on and it held the trunk lid up enough to allow the light to remain on. Unless you get in the trunk and have someone shut it it's real hard to tell. I guess you could pull teh bulb and see if the battery drains.

Check the dome light and the glove box light and the clock if equiped.

I have a 64 Falcon that has trunk light with a "mercury" type switch - switch was bad and would keep light on . . . would try above for sure

Disconnect the alt.leads & see it could be shorted.

Just a suggestion...
Pop off each bulkhead connector, 1 by 1....
See if the light goes OFF..
This may point U in the right direction..

Just my $0.02....

This. My '89 Diplomat fought me with this and it was the alternator.

Read ....He has disconnected the alternator.

My bad missed that.

Might be worth checking the fusible links in the harness.

One over looked item is the key light and relay. Something should be warm. What is the history and when did this start? Get it in a dark garage or go out at late night when it is very dark and look for something lit.

Converted ignition? Been a while but doesn't that have a ballast hook in? Where is that getting it's power?

I had one years ago on 63? T bird. Couldn't find it. It had the older analog clock that had points. When the clock spring needed to wound the points would close, wind the spring and the points would open. OK but this clock wasn't working so I blew by it. After chasing my tail for a few hours a buddy suggested disconnecting the clock. I said why? it's not working
Well lo and behold the points were stuck shut, which overwound the spring until it broke, so the clock motor was running all the time. But you couldn't hear it and I ASSumed it was not the issue.
might try the bulkheads as suggested as it might narrow it down. I would start with the wiper motor harness.
It has to be something that is hot all the time and not fused by the fuse box
A schematic would be very helpful as well
Keep us posted

Trying to shotgun electrical problems usually never ends well. Get a wiring diagram for your car. Based on that, start removing components one by one until the problem is found. I've been through this more than once and this typically has worked best for me.

Some circuits are not fused: HL,park,etc. Focus on those type circuits.

Just have to keep disconnecting stuff until it disappears. Relays, Connections. As stated, firewall connections to try to isolate it.

This
This
THIS
It helps you establish a map so you can isolate and work each circuit rather than get lost and chase your tail. You will be surprised at what else you may find that was goofed up by a prior owner as well.

https://mymopar.com/wiring/
doesn't go that new, but maybe 75 is close enough. cordoba would be similar.

there is a relay (3 wires) for the alternator, under passenger fender, has battery voltage at all times, unplug that

I'll check that. Thanks for everyone's input.
The owner bought the car recently from an estate, so he doesn't know much about it. The car is very low mileage and in excellent untouched condition.
The digital clock does not function though, so I do wonder if that is possibly drawing power

Not enough to turn a test light on. That's substantial. Something is stuck on.

Dang it me too. I try to read everything but once in awhile

Read my earlier reply

The clip on direct current measuring coils are very handy for tracing “sneak currents” in wires without cutting or disconnecting the wire.

These are called “Hall Effect” current sensors..
They used to cost $100 to $200 but have come down greatly in price.

https://www.fluke.com/en-us/learn/blog/clamps/inside-hall-effect-clamp-meters

https://www.amazon.com/BSIDE-ACM91-...Y2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

I've had aftermarket voltmeter gauges drain a battery also. If it has an aftermarket one, I'd check that.

[quote=demon]Working on a 78 Chrysler LeBaron. It's a low mileage car, absolutely stock and untouched, other than it has had an electronic ignition conversion to eliminate the Lean burn system.
So the issue is:
The battery will go dead in a day or so.

Brand new battery.


I pulled off the negative cable, and put a test light between the negative battery post, and the negative cable. The test light is bright.


You can't check voltage drain like that. The minute you put the leads on the post and cable it completed the circuit through the light bulb. It'll read 12 volts too if you use a meter hooked up that way. You need to check for amps.

Voltage gauges should always be hooked up to a switched source as they draw a current through the gauge to read the V.

One of the youtube channels I watch occasionally, ScannerDanner, he had what he called a cheat for something like this: a temperature camera. He was looking for an electrical issue in a late 70s ramcharger. The only drawback to check things this way is the component would have to be visible.

I disagree, in a non automotive situation try to get a bulb to light when its connected negative to negative.

In the case above think of the bulb as acting like an amp meter as it will illuminate as a current flows through it. It is connecting to positive though the device that is using the current.

Well as a union electrician I can tell you are mistaken. It is not going negative to negative. The positive cable is still hooked up. All you're doing is taking off the negative cable and hooking it back up with a light bulb in it. The bulb itself is load. Unless you unhook every harness off the battery it will light the bulb.

If you don't believe me go out to the garage an disconnect your negative cable and then get out a volt meter and put 1 end on the battery and the other on the disconnected cable. The meter will read 12 volts.

Wrong.

A bulb will show the "load"(resistance in the system that is draining the battery) but it's not going to tell you what the load is in millivolts. You need a meter to see what that is!

Hope this helps. Its step by step.

https://www.wikihow.com/Find-a-Parasitic-Battery-Drain

Of course you can. Inserting the light bulb between the battery and the cable completes nothing. It simply extended the cable. There still has to be a completed circuit between the two battery cables to light the bulb and that's what you are looking for, what is completing the circuit. As to volts vs. current, a voltmeter/test lamp/light bulb will show that there is a drain but you do need an ammeter to determine the magnitude of the drain.

AH, Moparts strikes again! It happens with nearly every question concerning an electrical problem.

We have competing experts saying the other guy is wrong and his testing methods won't work, but mine will.

Is there any wonder why non-electrical people are confused about electrical problems? I've done a lot of automotive electrical repairs, but you guys can confuse me.

The experts argue with each other on how its suppose to be tested and figured out, and all the guy wants to to solve his problem. Who is he suppose to believe?

How about, if YOU have actually SOLVED the particular problem on a similar car the OP has, write a step by step process. If you personally have not solved the problem, don't post. This should not be a location to test theory.

I saw the reply's from some people I respect on here and decided I needed to do more research. I'm always willing to listen and learn and I learned something new today.

Since 99.9% of my work is AC I needed to do some checking. Here's what I found was causing the difference of opinion.

Answer a DC test light is a tool with a normal open circuit that needs voltage to close to turn on light. So no it will not complete a circuit without voltage. Where an AC test light is just a closed circuit and will complete the circuit. ( yes I know it's a light bulb in a socket but that's all an ac test light is and i don't ever use them. I always use a meter).

The photo's show the ohm's and open circuit on the test tool.

I believe this source is still good info and would use a meter because almost ever car now has some draw (Clock,memory on radio & drivers ect.) that could turn the light on partially. Be sure and put the red lead in amp hole and set meter to DC amps. https://www.wikihow.com/Find-a-Parasitic-Battery-Drain

Only if there is something "ON" somewhere causing current to flow. No current flowing, no light. Measuring amps will accurately tell you how much the draw is pulling. An incandescent test light will also be useful by observing how bright the bulb is.

You have to be careful with newer cars that have auto-diming interior lights, chimes, and anything else that stays on for a period of time after the ignition is shut off. "Keep alive" circuits are very small, will take weeks to run a battery down and won't turn a test light on.

Disconnect negative terminal from battery. Connect a test light, ammeter, whatever, to indicate current flowing from - post to - terminal. Amperage or lights on indicates current flowing through something. Knowing how much amperage is flowing can be a clue as to what is on. Allow it to sit for a minute to verify that the draw doesn't disappear due to some timed circuit. A small light bulb or relay stuck maybe 1/4 to 1/2 amp. Other items staying energized will pull more.

Isolate and disconnect circuits until the draw goes away. Once you isolate the culprit, hook the other stuff back up to verify nothing else is going on.

A DC test light is a light bulb. Nothing more, nothing less. Only difference between it and the AC test light is the voltage rating of the bulb.

This is how it works. Unless you have some kind of drain (load) in the system the light won't light because it isn't a complete circuit. How do you find the problem? I already answered that. Get a wiring diagram and systematically start disconnecting anything that is a potential load in the electrical system. Yes, it's a PITA but it can be done, I've done it. Now it would be nice if there was some kind of cook book approach but every vehicle has it's quirks and it's own selection of electrical accessories. So every vehicle is going to be different. Some problems aren't solved with an "insert tab A into slot B" approach. This is one of them.

Just a comment, two rules of thumb, incandescent electric lights are current limiters, spark gaps are voltage limiters.

nothing to add, but i have the exact test light [black handle, serrated bulb case, wire color/size and clamp] you show, and have had that item for almost 55 years.

Update I was WRONG!

I cleaned the ends on the tester and it's a closed circuit as well. The meter didn't have enough power to overcome the dirty connection but the 12 volt battery did. And yes it's old as heck. Lol

now that we've stopped peeing over the fence has the OP found the issue yet ?

Google this> https://www.google.com/search?q=dan+sullivan+loadpro
His Youtube videos are great. You'll learn a lot. His invention is pretty awesome.

I don't know much about 78's yet check every relay, one by one, disconnect the hot lead going to it and and check the test light for off. Sounds like there is a chance wire chafe between hot to ground, or hot to another wire (or more).

Another handy tool to use is a non-contact (inductive) ammeter. I picked one up on Amazon for $40 when chasing a draw and it has been consistent and pretty accurate. All you have to do is put the clamp around a wire (or wiring harness) and it will tell you instantly how much current is flowing within, so you can chase where it's headed.

Price went up a few bucks, URL was too long for software to recognize, here's the link:
Amazon Inductive Ammeter Link

I kind of skipped through all of the posts and suggestions but I have a question for the OP. In your first post you state it's a new battery, did you have this battery draining issue before you put a new battery in? What if it's a bad (new) battery? Just saying.

It takes amperage to light the bulb, small parasitic draws .050 mA will not light the bulb but can drain the batt. over time,there is a large amp.draw somewhere,use a DVOM to ck.amp.draw so you know just how much actually is being pulled as long it's not greater then the DVOMs fuse,then you will need a shunt,but the good old test light between the cable & batt.works just fine, me personally I would be taking a close look at the no longer utilized lean burn wiring & the elect. ign. conversion.

While it is true that we have recently seen batteries that show 12v on a voltmeter but crap out under load, only to return to 12V, the test light draw test is not a battery. There is current flowing somewhere that it shouldn't be.

Just checked my two test lights:
Older Snap On incandescent: 45.7 ma
Newer digital LED: 5.6 ma

A test light is a very good tool for parasitic draw tests.

No, I have not found the issue yet. It's got me baffled.

Yes, the owner changed the battery because of it draining, and it still drains with the new battery.
He purchased the car from an estate recently, so we don't know any of it's previous history. But it is in very nice original condition

Not a clue if this is pertinent, Folks have a saturn, same problem. Ignition switch. You could pull the key out and think it was all off but it wasn't actually in the off position. Probably doesn't apply here.

Original radio or aftermarket with a power antenna?

Something is in there that is not fused and possibly something installed by the previous owner or something the original owner didn't know about.

You Are going to have to invest in an DVM or amp meter (digital preferably). in series is most accurate but the inductive pickup ones should suffice as well. I picked up one of these recently as my fluke was limited to 10 A without it's external probe which died. Nice meter for the $$. Do note there are different models as cheap as 25.00 . if one learns how to use it a little at at time it will become and indispensable tool METER LINKY

I gave up on finding the battery draw. The customer is taking it to an auto electric specialist.

Do keep us posted

I’m surprised how this played out. Seems there is unfused power and has to be one of a handful of factory things or some aftermarket item that could be traced to a hot spot.

I parted a 71 Dart years ago that had a fried underdash harness. I kept it for redoing the one in my 70 and when I opened up the fried one, I found the brake warning circuit wired wrong.
The downleg wire after the light was only connected to the e-brake switch, but the low fluid circuit was joined at the hot side.
Imagine trying to troubleshoot a hot wire smell that only occurs when the brake fluid is low, much less connecting those two dots!

You had a 70/71 Dart with a low brake fluid switch?

I can't remember if the 70 had one, but the 71 definitely did. It was built into the junction block.