I've replaced all the gauges in the dash with autometer, fuel, temp, oil pressure, tach, and speedo. They all work fine but when I turn the lights on to illuminate the back bulbs, the fuel and oil pressure peg out, and the speedo odometer looses power. I experimented with my own hot 12 volt to the lights and they come on and don't peg out, odometer stays on, but the fuel slowly rises to full instead of staying at a half tank. In the process my oil pressure is stuck pegged way past full. It's weird, it all seems to work fine when dash is out on the bench and I apply power gauges respond normal. When in the car it all goes to ****. I've got the multimeter out and checked my switched power for main, and switch for lights. all show 12 volts when tested. I'm stumped I know it's a mess of a lot of information, but if anyone can decipher out what's going on and knows a tip to start troubleshooting, I'd owe you one.

 

Sounds like you have a hot ground somewhere in the wiring for the lights. I'll bet one of the wires for the lights are shorting with something.

 

Either the above, or the ground path from the gauges is marginal, and when the light voltage is applied, it is feeding backwards thru the gauges.

 

What do the gauges do when you adjust the instrument cluster brightness from max to min?

 

Figured it out. I'm a retard and got my ground and lights/12v mixed around. All systems go.

Thanks for the help

 

Hey did u use the oem sensor? I am curious on how u got them fit and work on the oem cluster wires?
Khris

 

coughcough, ahem. lol