Elecrical problem On 1972 Duster

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Rodnutrandy

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Was helping a friend today on his 1972 Duster, Right brake light didn't work, wipers didn't work , a few other small items. We got the wipers fixed, and got the tail light to work (bad ground) , Here is the problem that has me stumped. If lights are on the turn signals front and back bleed to other side, both front and rear lights flash, If lights are off , the turn signals work as they should. Another item is the lights are dim unless you start the car , than they brighten up. Battery starts car fine and we even put a 40 am charger on the battery , which didn't help. All 4 light sockets were lightly corroded, Cleaned them up and checked and cleaned all grounds. Switched the 2 flashers and no change , See no breaks in wiring from front to back, cleaned connections at firewall. Also took any connectors apart and checked and cleaned them . Besides ground to engine, their is a ground from battery to radiator support . Any ideas would be appreciated.
 
still sounds like a bad ground somewhere, tail light or parking light.
 
Sounds like a bad ground to me. Could be in the front or rear. They must be grounding through the light bulb. You can get free wiring diagrams at mymopar.com .
 
X3 on the ground being the problem.
One thing you may like to know is that just because the light housing is grounded doesn't mean the socket is.
Some of these light housing had a separate metal piece (the socket) inserted into the housing and they can loose the ground there.

Ground a wire to the frame or somewhere else solid and while the lights are on touch the bulb base with the grounded wire.
That should send you in the right direction.
 
I cant get my head around what you're describing. When a ground fault in front park/turn fixtures is present, the signal indicators in the dash will come on with park lamps. You haven't mentioned those so...
I'll just imagine for a moment that this electrical system is so weak that park lamp element brightens and dims with the added draw of headlights and turn signals. Makes more sense to me than "bleeding" ?
What folks don't quite get, There's a huge wire from battery to starter. That much works well. Everything else is operating on a much smaller wire. This wire goes through bulkhead connections, ALT' gauge, and weld splices under dash. For things to work good they'll need both + and - to be good.
 
Possibility of one of the dual filament bulbs having a crossed filament?
 
All good ideas , I did try grounding the sockets with a jumper wire , also ran a wire from connection at front of drivers door to the tail lights , didn't change , The indicators for flashers and turn signals work as they should . I added a ground at front of car by splicing in the ground wire and taking it to the radiator support, we removed rear ground and cleaned every part to make good connection . I agree , I thought it was ground , but now have to check battery grounds , even thou if starting car with no problem , you would think ground is good enough for lights , I will go back over and try some other checking! And take 4 new bulbs with me! Thank you for all comments!
 
I would pull all the tail / park bulb and check each one. you can put them on a battery with a jumper and light one filament at a time. Make sure one filament is not welded over to the remaining one.

Check (recheck) grounds using a meter or 12V test lamp. Get the system in a situation to be "acting up" and then go round to each lamp shell and probe the lamp shell to a good ground. There should be no voltage / no test lamp.

If necessary, take a long length of wire and clip it to battery NEG so you have a known good ground for the meter / test lamp

You can access the turn signal connector at the column. Using the service manual, identify the left / right/ front/ rear turn and check each output with a meter or test lamp when activated.

If you get the system "acting up," also try pulling the "unused" two bulbs, that is, if you have left turn on, pull both right hand bulbs.

Is there evidence of a short somewhere? That is by smell or melted harness? Often a short will heat up and melt wires together, forming unwanted cross-connections. THESE can be difficult to find.

Yet another thing you can do is get the system acting up, and pull the lighting harness connector off at the bulkhead connector. See if the rear continues to act up.

Conversely, pull the rear harness loose at the left kick panel. See if the fronts continue to act up
 
Ok ,put another 6 hours on Duster today. Started at battery, Cleaned posts and block and frame ground , That bleeding is going thru complete car, even the radio fades in and out , here is questions , Battery shows 11.7 volts , Alternator only charges at 12.5 and hardly any at idle . Shouldn't the alternator be close to 14 volts and battery at 12.6 ? All grounds are good , even took steering wheel off and cleaned the turn signal switch . I am going at battery and alternator next , Starts good and runs down road , but seems needs more voltage. We ran a new wire from at drivers front of door to the rear lights , no brighter. Thanks for ideas !
 
Rodnutrandy said:
, Battery shows 11.7 volts , Alternator only charges at 12.5 and hardly any at idle . Shouldn't the alternator be close to 14 volts and battery at 12.6 ?
Click to expand...

Yes, fully charged battery after surface charge, and everything off should be about 12.6, and running / charging should be no less than 13.5, no more than 14.5, and opitimal (when warm) 13.8---14.2

So basically it's not charging for whatever reason.

I would do a "quick check" to find out if the alternator is capable of charging

1...Check belt. Don't laugh. Signs of slippage? loose?

2...Do a "full field" charge test. This involves applying full battery voltage to the alternator field

The way the 72 system works, is you have two field wires. Blue is switched "ignition run" battery voltage direct to the field, this is a branch same power goes to ignition and voltage regulator

However DO NOT assume that this is "OK"

Disconnect green field wire. Jumper that alternator terminal to ground. Turn the key to "run" with engine stopped. Measure voltage at the blue wire field terminal, leaving it hooked up Should be "same as battery"

A quick check is to ground / unground your jumper wire, you should see a small spark. If you know how to measure current, "rig" your meter for current and check field current draw. Should be more than 3A, less than 5-6

Now start and run, check battery voltage. Bring RPM up slow. Battery voltage should climb right up. Keep voltage below 16 and don't rev very high until you see what it does

If battery voltage remains fairly low, move your meter to the alternator "big stud." If voltage is really high, there is a disconnect / break in charging wire path to battery. If voltage is still low, below 14-15 with engine RPM "up" then alternator is bad
 
You're on the right track now. Everything works better with proper power supply.
I had a Chevy Lumina ( ex police cruiser ) here once that seemed fine most of the time. When it randomly failed to start it would short cycle its electric fuel pump with the turn signals. Hazard flasher switch in the dash would make a weird buzzing noise when on. Body control module ? nope. Crossed circuit at that hazard switch ? nope.
The contacts in the ignition switch were the culprit.
 
So not charging at idle. Maybe not your problem but it was mine. I put a new alternator on the spouses car and didn't give much thought to the pulley size. It was to large and never allowed for excitement at low rpm's. Changed the 3.5" pulley for a 1.75" and problem was solved.
 
Here is plan for later in week, Taking Alternator to have it checked, Before taking alternator of, jump across the amp gauge and see if it effects anything, Check water in battery ( a little late on this one) , If alternator checks ok, don't think it will , check battery. Next ,f none of this helps , run a heavy wire from alternator to positive post of battery to by pass the amp gauge , remove amp meter and install a volt meter in car . Thanks for all the comments , been a big help , I will update as we get it cornered !
 
Sounds like you have the typical bulkhead connector issue as well...
 
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