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Need some electrical guidance

hunt2elk

hunt2elk

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So this car is my 1970 Duster with the standard dash. I realize this is not a 'B' body, but have to imagine the wiring is similar. I am not the best by any means with the wiring on these old cars. Need some help to get me pointed in the right direction on this strange issue that happened last evening.
With the engine running and I pull out the light switch to get the parking lights on, both the temp and fuel gauge peg to the right as well as both turn signal indicator lamps in the dash cluster come on dim.
With the motor not running, everything works fine. I tried it with the ignition switch off as well as in the run mode.
Anybody have any ideas?
 
Sound like a ground problem to me. Is your wiring all original? Have you had anything apart lately?
 
Almost all strange electrical problems source back to 1 or more bad grounds. There is usually no quick “silver bullet fix”with nearly 50 year old wiring. Start at the front of the car and remove and clean every ground point. Don’t forget all the light bulb sockets too. Sandpaper and or a Dremel work great. Use a corrosion inhibitor when you put them back together. Vaseline is cheap, or use a deox product. Make sure the steering column ground is good. Take the cluster out and clean all the contacts. It never hurts on mopars to clean the firewall connector too. If all that doesnt work then start tracing out the wires to those circuits looking for another problem like chafed or melted wires.
 
With the engine running and the lights off, do the gauges act ok?

Years ago I had the cluster out in my 66 Belvedere to replace burned out bulbs. I stuck it back in place to see if all the new bulbs worked but didn't put any screws back in that hold the cluster to the dash. Talk about things going nuts! The electrical system went nuts! The sad part is that it took me a couple of hours to finally think that maybe the cluster grounded to the dash frame via the screws! Talk about feeling dumb lol
 
Cranky said:
With the engine running and the lights off, do the gauges act ok?
Click to expand...
Yes, everything is fine. I hardly ever drive my old cars at night, so this may have been going on for a while.
 
Cranky said:
Sound like a ground problem to me. Is your wiring all original? Have you had anything apart lately?
Click to expand...
All wiring was new M&H 2 years ago. Nothing has been apart since the resto.
 
I think everyone's comments are on the right track. I had a similar scenario with my Charger a while back where my volt gauge pegged and no fuel gauge or temp gauge with the engine running. Every thing seemed to work fine with just the ignition on. I pulled the cluster and crimped the push on connectors on the back of the cluster as a couple of them seemed too loose. It fixed the problem. Poor grounds and poor connections cause tons of issues. I'm sure it is a bad connection somewhere on your cluster.
 
Check high low bean switch at floor. Is connected to light switch at dash. For loose wires and ground. If I remember, Main wiring harness Splice on that circuit..
 
Do one circuit at a time so you don't go crazy. I would invest in a power probe if you are not great at wiring. The probe can be your friend. Watch the videos on how to work it and then have some fun you will find alot of problems you didn't think you had. But most of all check what everyone else says
 
Checked all my grounds and they were fine. Made sure the main connector on the back of the circuit board was pushed on good. I did find a loose bulb in one of my aftermarket gauges hanging under the dash, but doubt that had anything to do with this issue. I used grease on every electrical connection when I put the car together 2 years ago. I also had run a separate ground wire to the steering column. Maybe I will run another ground wire up to the dash just for the heck of it. So as of now, everything is back to working the way it should. Just weird though. I have been around these cars all my life and have never seen the gauges peg to the right unless grounded.
 
If it is not a ground problem and you installed new wiring and this is first you used lights you may be feeding 10 volts into the 5 volt circuit from the light switch as in dash lights
 
bm02tj said:
If it is not a ground problem and you installed new wiring and this is first you used lights you may be feeding 10 volts into the 5 volt circuit from the light switch as in dash lights
Click to expand...
The wiring was all new 2 years ago. Everything was working fine last summer when I used the lights.
 
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