I have just converted my car over to the factory gage set up. Everything works except oil press. When you turn on the ignition ( engine not running) it pegs out at the top (H). I have rechecked the wiring and it is correct. Disconnecting the sending unit makes no difference. Same with engine running or not. With the ignition off needle sits in the middle. Any suggestions appreciated. Thanks Paul o No:
If it only happens when the motor is cranking, it is because the ground that is used to check the temp light is connected at the ignition switch. Once you stop cranking and the ignition is in "run" the guage will work normally. This happend to me as well. Just trace the ground wire at the ignition switch and remove it and tape it so it won't touch anything. It should solve your problem. Mark
Mark: Thanks for your reply, but it is when the ignition is in the run position engine running or not. Any ideas??
Go through the wiring again. With the ignition on the oil and temp should go to L and C. Sounds like something is backwards with the power. If you switched the wires in the plug, you could be one off. Some gauges had an adapter harness that did the switching for the wires. Other than that, the gauge could be bad. Maybe others have some ideas. Mark
The resistors on the back must be installed correctly. One, either water or oil, will fit in two different positions. This made mine peg out at max. when plugged into the car. I bought a "restored" unit & he put it together incorrectly. Go to George N.'s site & find his article on guage installation. There is a pic of the back showing the resistors in the right places. www.buickperformance.com
Could also be that the wire from the sending unit to the dash is grounded somewhere. With everything off connect an ohmmeter between the sending unit end of the wire and ground. Should not register. If it does, you have a short in that wire.
I've since checked my old notes. The resistor that can be reversed is for water. Left side indicator facing the front of the guage, right side facing the rear.
