Hey guys , I haven't been here in a while . I am having an issue with my instrument cluster . I will say that the car has been sitting for a few months and the issue was intermittent but now is not going away . The ic acts normally until I pull the headlight switch , then the gauges seem to go dead except for the speedo . Turn the switch off and back to normal .
I am retired now and not as nimble as I used to be , so I would like to have a direction to go instead of just replacing parts until I find the right one .
Thanks for the help !!

 

You are describing the classic symptom of a bad ground, and your gauges are finding their ground path through the non illuminated dash lights when the switch is off. It could be anywhere in the ground circuit, one common place is the connectors where the gauge unit plugs into the dash can get corroded and slowly begin loosing connection. If this were mine I'd start by getting the pinout of the gauge unit connectors for your car's specific year , take the gauge unit out, and check whichever connections are supposed to be ground with a meter to see that they are, in fact, grounded.

 

Thanks orangebird !!! Thats helps a bunch and makes sense since the car has been sitting . I will check it out and confirm fix .

 

Your Welcome, and I hope the bad connection is easily found

 

We will have to wait until the OP makes another Post.

For any of you who has read through this Thread, and is confused about the Speedometer operating properly.
The Speedometer is cable driven (and not Electric) thus it is not affected.

 

So i have a problem where my speedo works and so does the tach (it pegs but i know thats the resistor) the voltage gauge reads correct as well but the fuel, oil press and temp gauges do not seem to be working. The oil pressure drops to 30 with the key off and pegs when on. The fuel gauge reads empty when the key is on but when you turn it off it slowly goes up to about 1/8. The temp gauge just kinda sits around 120 or so it moves a tiny bit but I don't think it ever gets more than 140 or so. So does this sound like a ground problem or something since the speedo works?
BTW it's a 92 RS V8.
Thanks.