Instrument light issue

[86M10086.2L]

The instrument lights on the dash of my truck stopped working. Whenever you try to turn them on. The fuel gauge zeros out and the right turn signal indicator on the dash comes on. I also get a little feedback coming through the high ram indicator. All the other lights and gauges still work properly including the turn signals and the lights for the accessory gauges that are hooked up to the same circuit. When the instrument lights are off everything is fine. It sounds to me like there's a bad ground. But I've checked everyone I can find with no improvement of the symptom. I've done the ground under the dash by the emergency brake lever. And the grounds at both turn signal lamps. I also disassembled the headlamp switch and saw no signs of burning corrosion or failure. Are there any other grounds I may be missing or missed? Or could it actually be the headlamp switch?

 

[AECS]

I think it is time to tear into that dash and clean all the contacts on your instrument panel flex print circuit. Could be the ground, I would need to have the schematic in front of me, but it all hinges on where all the various lights get ground. I believe the turn signals get their ground at the grill/tail lights, so that a failure is indicated on your dash, all your warning lights get theirs from the sending unit/alternator relay. So the problem you describe very well could be the ground.

 

[86M10086.2L]

I did a thorough cleaning a few years back when I first got the truck. As only some of the lights worked. After that everything was great up until recently. I guess there's not many other options except taking the dash out and trying again.

 

[joshuak]

... I also disassembled the headlamp switch and saw no signs of burning corrosion or failure. Are there any other grounds I may be missing or missed? ...

There is a sticky covering the CUCV Electrical Ground Locations, found here: http://www.steelsoldiers.com/showthread.php?123199-CUCV-Helpful-Threads.

I have had similar malfunctions, where my dash light turn signal has come on (dimly) when I turned my head lights on. Cleaning the right front turn signal socket fixed it once and replacing a non functional light bulb fixed it on another occasion.

Good luck.