Unusual electrical problem?
Thread Starter
Burning Brakes
Joined: Mar 2002
Posts: 792
Likes: 1
From: Louisiana, It's Always Party Time!
Unusual electrical problem?
Just got through installing a new radio and was putting all the consoles back in. Started the car up and everything looked good. All guages worked. Wanted to check the light to the AC panel so I pulled the headlight switch and my gauges quit working. The gas gauge went to empty, the oil gauge dropped to 0 and the volt meter dropped to zero. Turned the lights off and they started working again. Puzzled I tried the headlight switch again and the gauges quit working again. Turned the headlight **** to dim the lights and the guages came back on. The guages only seem to work when the dimmer is off or nearly off when the headlight switch is on. I brighted the dash lights back up and the gauges go to zero. 
Is the problem in the headlight switch or possibly somewhere else? I thought of the new radio and killed the power to it and the same problem occured. Any suggestions or ideas would be greatly appreciated.
Thanks
Jay
Is the problem in the headlight switch or possibly somewhere else? I thought of the new radio and killed the power to it and the same problem occured. Any suggestions or ideas would be greatly appreciated.
Thanks
Jay
Thread Starter
Burning Brakes
Joined: Mar 2002
Posts: 792
Likes: 1
From: Louisiana, It's Always Party Time!
KapsSA,
I replaced an aftermarket radio that the previous owner had put in and saw no grey wire. I used the same wiring that was used on that radio for the new radio except I replaced a section of wiring for the memory of the radio. The problem only occurs when I turn on the lights. Guages work great when the lights are off but drop to zero when the lights are turned on. Gauges will again work when the dash lights are dimmed as far as they can go.
Very perplexed to say the least.
I replaced an aftermarket radio that the previous owner had put in and saw no grey wire. I used the same wiring that was used on that radio for the new radio except I replaced a section of wiring for the memory of the radio. The problem only occurs when I turn on the lights. Guages work great when the lights are off but drop to zero when the lights are turned on. Gauges will again work when the dash lights are dimmed as far as they can go.
Very perplexed to say the least.
Safety Car
Joined: Jun 2004
Posts: 4,372
Likes: 223
From: Beecher Illinois
OK, with an aftermarket radio I assume they cut the plugs off the harness. The original harness for radio power(not speakers) would have 2 yellows, a black and a gray. I'm pretty sure 80s didn't yet have electronic radios from the factory. With that in mind, you would need to run a new hot wire for memory(like to the lighter or all the way to the fuse box). The gray wire that should be there somewhere is for the dash lights. If it's grounded or hooked up somewhere it shouldn't be maybe it's causing the problem. Find that gray. Should be wrapped in that bundle of 4 wires for radio power.
Radio only change you made?
Mike
Radio only change you made?
Mike
Thread Starter
Burning Brakes
Joined: Mar 2002
Posts: 792
Likes: 1
From: Louisiana, It's Always Party Time!
Will check for grey wire. Getting cold and dark in garage so it will probably have to wait until tomorrow. Only change was to the radio. The memory hot wire is off the lighter. That's is were I made my wire change. Went to a larger wire. The wiring harness that goes to the gauges is a large harness that plugs into the back of the circuit board. I unpluged it to remove the guage assembly (new bezel) and then plugged it back in once the radio was wired up and ready for installation. Obviously, I have either not reconnected something in the area of the radio or something has gone bad. I still find it unusual that everything works great when the lights are off but the gauges seem to lose power when the lights are turned on. Then if I adjust the dimmer switch on the headlight switch the guages come on if I turn the dimmer completely off (no dash lights) 
Le Mans Master
Joined: Jan 2000
Posts: 8,918
Likes: 27
From: New Hill NC
Yep you lost the ground. Go back to the circuit board plug and look closely at the metal tabs on the circuit board. You are going to find one that has come loose and moved when you repluged it.
Thread Starter
Burning Brakes
Joined: Mar 2002
Posts: 792
Likes: 1
From: Louisiana, It's Always Party Time!
Well, I jst got through tearing the consoles back out and unplugging the harness from the gauge cluster. Nothing really looked out of place but I proceeded to cleanup the contacts on the harness plug and very qently cleaned the contacts on the gauge cluster board. Plugged it back in, started the car and the guages worked. Then I (crossing fingers here) turned on the lights. Guages continued to work properly. 
I turned the dimmer on the light switch and everything still worked fine. 
So, it looks like there must have been a bad contact between the harness plug and guage circuit board.
Thanks to KapsSA, big_G & wombvette for your suggestions and ideas.
Jay
I turned the dimmer on the light switch and everything still worked fine. So, it looks like there must have been a bad contact between the harness plug and guage circuit board.Thanks to KapsSA, big_G & wombvette for your suggestions and ideas.
Jay
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Intermediate
Joined: Apr 2005
Posts: 38
Likes: 0
Originally Posted by KapsSA
OK, with an aftermarket radio I assume they cut the plugs off the harness. The original harness for radio power(not speakers) would have 2 yellows, a black and a gray. I'm pretty sure 80s didn't yet have electronic radios from the factory. With that in mind, you would need to run a new hot wire for memory(like to the lighter or all the way to the fuse box). The gray wire that should be there somewhere is for the dash lights. If it's grounded or hooked up somewhere it shouldn't be maybe it's causing the problem. Find that gray. Should be wrapped in that bundle of 4 wires for radio power.
Radio only change you made?
Mike
Radio only change you made?
Mike
Mike, where does that gray wire go, I have no dash lights.
Lobo2001 thanks you
Melting Slicks
Joined: Jul 2005
Posts: 2,740
Likes: 3
From: Aurora Ontario
Originally Posted by lobo2001
Mike, where does that gray wire go, I have no dash lights.
Lobo2001 thanks you
Lobo2001 thanks you
Your problem is quite likely in the dimmer part of your headlight switch. there is a coil there that has a contact tha slides along it increasing or decreasing the voltage to your dash lights as you turn the ****. When the coil breaks and depending on where you may get no power to the dash lights.
Jim