I'm trying to troubleshoot the oil pressure gauge in a 91 Spirit R/T dash. When I start the car, the gauge pins to as low as the needle can possibly go (9 o'clock position). I've done everything I can think of to try to figure out the problem and am stumped. Here's what I have tried so far:
- Installed a mechanical gauge and determined oil pressure is well within spec
- Swapped in cluster from another Spirit R/T: the cluster from the other R/T did the same thing and this cluster worked fine in the other R/T
- Tested the oil pressure sending unit/switch: tested OK, but bought new one anyway and no change (also swapped known good sending unit from other R/T and that did not work either)
- Ohmed out the gray/yellow wire and it tests clean from sending unit all the way to instrument cluster
It looks like the circuit is a simple one wire from the sending unit to the gauge and all the gauge does is measure the resistance that the sending unit puts out. So I'm stumped as to what could be causing the gauge to do what its doing. Does anyone have any ideas on what I might be missing?
And no, I don't really want to permanently install the mechanical gauge, so that suggestion is off the table. LOL!