I'm pretty sure I've seen it under the car several times before. I looked in my manual and it shows it's on the driver's side but that's about it. (LO3) To me, the logical place for it to be would be right near the oil filter. I bought the part already so at least I have something to match it up to or compare it with.

On a side note, how would a malfunctioning switch cause a code 54 to trip.

Side note, I dont know.

Im guessing on the years, but 88-up the sender is a 2 wire deal thats up above the oil filter. It sticks out of the side of the block towards the side of the car. It sits level with the ground. I could go measure it, but its like 1-1.5" above the mounting pad for the oil filter.

the oil pressure switch on my gta is right above the oil cooler. I believe a code 54 is low fuel pump voltage, which really doesn't have anything to do with the switch itself because the switch is simply an on-off deal nothing in between. If it was messed up, the fuel pump would get no voltage and the car wouldn't run. I assume the car is running. Also, the oil switch runs a parallel circuit to the fuel pump relay circuit so that it can still power the fuel pump should the relay fail. So if the switch itself is bad, it still wouldn't stop the pump..

Yea, after digging up some wiring schematics I see that the switch and fuel pump relay seem to be on the same circuit. madmax, thanks. You pretty much verified where I thought it was. By the way, the car runs just fine. Startup is the problem. It's either the relay or the switch. I plan on replacing both in the morning. Thanks.