Question, since I used a PSI harness and separate fuse block for the fuel pump, can I cut the grey and orange wires off the oil pressure sender connecter and just leave the tan reference wire for the stock 1991 gauges, or do I need to run both the other wires for it to read oil pressure gauge to work?
Using the stock sender but also have the post 98 ls-1 oil sender as well.

 

the ls doesnt care about oil pressure you can use the single wire. 2001 silverados used the one wire oil pressure sender. same plug

 

Copy that, thank you.

 

It would not surprise me if 1998 Camaro has a unique oil pressure sensor to that year car. You might want to look into what is different about it from 1999 and whether it will work well with your gauges.

 

IIRC: 98 was a 3 wire sensor that provided separate signals to the PCM and gauge. 99+ went to a two wire sensor that sent signal to the PCM (or BCM, cant remembered) and from there it went to the gauge.

 

This is true with the coolant temp sensor but I don't think this is true for the oil.

EDIT: It appears that you are right. I think it is 4 terminals vs 2.

1998 - 12551640, 12559781, 19244504
1999+ - 12562267

 

I’ve read that you can use either the stock 3 pin 3rd gen oil sender or the 99-02 oil sender? It’s looks like the Ls-1 stock sender is 1 pin which is in the center of plug and the stock 3rd gen 3 wire plug, the center pin is for the gauge. The other two wires are for fuel pump relay it seems.