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Lights dim/flicker at idle
#1323489
10/20/12 06:28 PM
10/20/12 06:28 PM
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Joined: Jan 2011
Posts: 15,806
Central Florida
larrymopar360
OP
Stud Muffin
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OP
Stud Muffin
Joined: Jan 2011
Posts: 15,806
Central Florida
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The lights (headlights, dash lights) dim greatly at idle, and then brighten back with any increase in idle on my mostly stock '89 Diplomat police car. There is a bit of flickering too. When I first got the car I immediately had the alternator rebuilt because car had sat so long and I didn't want to chance it. I also have replaced the voltage regulator. I really don't know if it was doing this before I replaced these things because I didn't drive it at night prior. The battery cables look fine, and I cleaned the ground cable to the block real well. Seems to be charging ok, but continues to dim and flicker. It is the 100 amp police alternator, and it does this even when the only thing turned on is the headlights. My others don't do this. It is a very noticable dimming/brightening/flickering. What to I try next? Thanks.
Facts are stubborn things.
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Re: Lights dim at idle
[Re: larrymopar360]
#1323490
10/20/12 06:47 PM
10/20/12 06:47 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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I'd clean the bulkhead halves thoroughly along with the rest of the charging circuit and grounds. That solved my dim at idle/brightening when speeded up issue
live every 24 hour block of time like it's your last day on earth
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Re: Lights dim at idle
[Re: scratchnfotraction]
#1323492
11/17/12 09:26 PM
11/17/12 09:26 PM
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Joined: Jan 2011
Posts: 15,806
Central Florida
larrymopar360
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Stud Muffin
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Stud Muffin
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Central Florida
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Still have this problem. I cleaned up all the grounds I can see. Ran another ground wire from VR too (also has factory ground straps all over the place including from VR to hood). The fusable link along the drivers side underhood looks ok...if that means anything. The problem is definetly more than just a low idle. The clock on the radio is flashing dimmer and brighter with the turn signals too. Stopped by a good auto electric shop in town. He suggested it could be the ignition switch. Anybody have any thoughts on that? He said he would spend a little time checking it out one day, but it is at $85 an hour.
Wondering, could it be the connections at the starter, or is that not likely? Thanks.
Facts are stubborn things.
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Re: Lights dim at idle
[Re: RapidRobert]
#1323494
11/17/12 10:10 PM
11/17/12 10:10 PM
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Joined: Jan 2011
Posts: 15,806
Central Florida
larrymopar360
OP
Stud Muffin
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Stud Muffin
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Central Florida
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I could give that a shot (the other cars are fine). I did swap one of the other Voltage Regulators but same issue. I was wondering if the battery could actually cause this issue too...was thinking about swapping that out too. Thanks.
Facts are stubborn things.
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Re: Lights dim at idle
[Re: larrymopar360]
#1323495
11/17/12 11:14 PM
11/17/12 11:14 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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To me I think the flickering means that there's a variation on the demand side (accessories/devices being fed) & I dont think that's the case or a variation on the supply side (the alt). Yes if you have another 100 amper I would swap it & see what comes of that
live every 24 hour block of time like it's your last day on earth
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Re: Lights dim at idle
[Re: RapidRobert]
#1323496
11/18/12 12:22 AM
11/18/12 12:22 AM
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Joined: Jan 2011
Posts: 15,806
Central Florida
larrymopar360
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Stud Muffin
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Stud Muffin
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Posts: 15,806
Central Florida
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I am going to try swapping the alternators asap (hopefully get a chance in the next day or two). It's driving me nuts!
Facts are stubborn things.
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Re: Lights dim at idle
[Re: 1_WILD_RT]
#1323499
11/18/12 11:14 AM
11/18/12 11:14 AM
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Joined: May 2005
Posts: 4,704
Florida
BDW
master
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master
Joined: May 2005
Posts: 4,704
Florida
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Quote:
Quit wasting time & just add relays for high & low beams.. 
What he said, x2
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Re: Lights dim at idle
[Re: ahy]
#1323500
11/18/12 02:38 PM
11/18/12 02:38 PM
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Joined: Jan 2011
Posts: 15,806
Central Florida
larrymopar360
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Stud Muffin
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Central Florida
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I really appreciate the input here because I am stuck. Ahy: yes, stock pulleys. I have two other ex police cars with the 100 amp alts and no dimming. It does have the same heavy gauge wire on the alternator like the other cars and I have cleaned it up real well too. The flickering now has me much more concerned than the dimming. The dash lights, clock on radio, etc. flicker and especially when I have a turn signal on. If I can at least try a few things first then maybe take it to the $85/hr guy to check it out. Thanks!
Facts are stubborn things.
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Re: Lights dim at idle
[Re: Supercuda]
#1323504
11/18/12 08:22 PM
11/18/12 08:22 PM
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Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
DaytonaTurbo
Too Many Posts
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Too Many Posts
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
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Quote:
Quote:
Replace/run a new heavy gauge wire from the alternator output straight to the battery +. I don't know how your diplomat is wired as the older mopars ran this wire through the firewall to the ammeter, then to the battery. Sometimes the old wires can get all corroded inside and lose conductivity even though they visually look fine.
Not applicable to the Diplomat, it uses a shunt resistor to drive the ammeter. So the current never passes thru the bulkhead connection. Sounds like the alternator is flaky to me. Possibly a diode issue internal to it.
Yes but there's nothing to say his stock 30 year old piece of wire going from the alternator to the battery isn't pooched. New connector at the alternator end? New battery terminals? I agree that swapping the alternator is something he should try before mucking around with the wiring.
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Re: Lights dim at idle
[Re: larrymopar360]
#1323506
11/21/12 06:21 PM
11/21/12 06:21 PM
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Joined: Jan 2011
Posts: 15,806
Central Florida
larrymopar360
OP
Stud Muffin
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Stud Muffin
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Central Florida
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Darn it, not the alternator. I swapped them last night and same flickering of dash lights, radio clock, etc.
Don't know why I didn't think of trying this before, but today I turned the key on (not started) and with just the radio on, I turned on a turn signal. The clock on radio flashed with signal bigtime. Does this eliminate anything since the engine wasn't running. Could it be something with the battery? They are a bit of a pain to swap with the Thermoguards, but will gladly try it if it isn't a complete waste of time. Thank you.
Facts are stubborn things.
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Re: Lights dim at idle
[Re: larrymopar360]
#1323508
11/21/12 08:08 PM
11/21/12 08:08 PM
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Joined: Dec 2007
Posts: 1,357
central Florida
VL21
pro stock
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pro stock
Joined: Dec 2007
Posts: 1,357
central Florida
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First, I am an electrical idiot.
Just for something to try, and eliminate the switch, try switch off. Lights on. Then pull on the 4 way flashers. Bypasses the ign switch.
This will probably still pulsate the clock.
I think there is a bad ground somewhere, you may have a bulb filament shorting across or something, or bad firewall connection?
The whole dash panel cluster surround is made of plastic on your car, make sure it is functionally grounded.
While the lights are flashing, walk around, looking for something that is on or pulsing that shouldn't be. Maybe something is being back fed. Dome lights, trailer wiring? If this is a Fla car and has an aftermarket hitch, it is almost guaranteed that scotch locks or that ilk was used to wire in the trailer plug. OK,ok, I've done it myself too.
It takes gasoline to interest me.
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Re: Lights dim at idle
[Re: VL21]
#1323509
11/21/12 09:02 PM
11/21/12 09:02 PM
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Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
1_WILD_RT
Management Trainee
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Management Trainee
Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
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OK I'm gonna waste my time & try to explain this... Your headlights, turn signals, parking lights & dash lights are all fed by the same overloaded wire... When ever your headlights are on they aren't as bright as you'd like because they don't receive as much power as they would like.... Add the drain of turn signals & the headlights get even less power so they dim, the dash lights dim, the heater blower slows down (also fed by the same overloaded wire) All these loads cause the bulkhead connector to overheat which just amplifies the problem.......
Solution Add relays to feed the higher powered circuits such as high & low beam head lights & the blower motor.... Now these items work properly because they receive a dedicated power source, the previously over loaded bulkhead connector suddenly doesn't carry more than a few amps & all the minor loads receive full voltage causing them to work better too...
Oh BTW If you have more options like power windows or a power top on your car the original problem is worse but the solution is still relatively simple & even more effective....
"The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."
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Re: Lights dim at idle
[Re: 1_WILD_RT]
#1323510
11/21/12 09:09 PM
11/21/12 09:09 PM
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Joined: Jan 2011
Posts: 15,806
Central Florida
larrymopar360
OP
Stud Muffin
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OP
Stud Muffin
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Posts: 15,806
Central Florida
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Please forget about the dimming of the headlights. I wish I hadn't mentioned that now. IT IS THE FLICKERING that has me most concerned now. The headlights flicker (NOT JUST DIM)when idling, along with dash lights, etc. Everything that is lit is flickering. Put a turn signal on and the clock almost flashes completely off and back on with the signal. This is definetly not normal. I apologize for any confusion, but I have mentioned in several previous posts now that it is the FLICKERING of lights that I am looking to address, NOT THE DIMMING, although my guess is once I figure out what is causing the flickering the excessive (not just a little) dimming will go away. Thanks.
Facts are stubborn things.
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Re: Lights dim at idle
[Re: larrymopar360]
#1323511
11/21/12 09:14 PM
11/21/12 09:14 PM
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Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
1_WILD_RT
Management Trainee
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Management Trainee
Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
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Dimming & Flickering are related, they both indicate excessive resistance in the circuit.... The system was poorly designed 40 years ago & now has 40 years worth of corrosion adding to the resistance which is why adding relays is effective... Do what you want, I'm done...
"The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."
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Re: Lights dim at idle
[Re: VL21]
#1323512
11/21/12 09:15 PM
11/21/12 09:15 PM
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Joined: Jan 2011
Posts: 15,806
Central Florida
larrymopar360
OP
Stud Muffin
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OP
Stud Muffin
Joined: Jan 2011
Posts: 15,806
Central Florida
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Quote:
First, I am an electrical idiot.
Just for something to try, and eliminate the switch, try switch off. Lights on. Then pull on the 4 way flashers. Bypasses the ign switch.
This will probably still pulsate the clock.
I think there is a bad ground somewhere, you may have a bulb filament shorting across or something, or bad firewall connection?
The whole dash panel cluster surround is made of plastic on your car, make sure it is functionally grounded.
While the lights are flashing, walk around, looking for something that is on or pulsing that shouldn't be. Maybe something is being back fed. Dome lights, trailer wiring? If this is a Fla car and has an aftermarket hitch, it is almost guaranteed that scotch locks or that ilk was used to wire in the trailer plug. OK,ok, I've done it myself too.
If I am understanding what you are saying, the clock won't be lit up to see flashing because the key is off.
I have cleaned all the grounds and contacts. The thing I haven't cleaned is the positive cable at the starter, which I planned to do even though I can't see how that would be causing it, but I don't know. No trailer wiring ever. It is an old police car so it did have sirens and lights wired to front, so who knows with that stuff, but I don't see any obvious bare wires or wierdness. So short on time right now that I do a little at a time and then off to work.
Facts are stubborn things.
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Re: Lights dim at idle
[Re: larrymopar360]
#1323514
11/21/12 09:39 PM
11/21/12 09:39 PM
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Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
1_WILD_RT
Management Trainee
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Management Trainee
Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
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The deal your electrical guy is pointing toward is a connector coming out of the steering column... It feed to & returns from the ignition switch... Pretty common to have it burned like the picture below... But that feeds switched loads & the headlights aren't....
The thing is once you learn to add relays & see how effective they are as well as how cheap you'll be adding them to vehicles that aren't giving you trouble just because it makes for a better vehicle..
"The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."
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Re: Lights dim at idle
[Re: mopar_man]
#1323517
11/27/12 10:07 PM
11/27/12 10:07 PM
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Joined: Jan 2011
Posts: 15,806
Central Florida
larrymopar360
OP
Stud Muffin
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OP
Stud Muffin
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Posts: 15,806
Central Florida
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If I turn the key on but not start the engine, and turn the radio on and a turn signal, the clock light on the radio goes almost completely off and back on with each blink of the signal. Also cuts the radio sound out for a second or two on the first blink of signal, and then just the clock flashes on and off. This happens with no headlights on or anything else. Just key on, radio and a turn signal. So it isn't the idle speed. Thank you.
Facts are stubborn things.
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