Hi all..
I need some help! I have a 1988 D100 5.2 TBI. I replaced the oil pressure sending unit due to leaking and after installing the new one..the gauge was not working. Thought I got a bad one. Got another switch and same thing. Have a pulse at the switch. Jumped wiring at switch and guage moves. Pulled dash and found that someone has been there before due to the oil light bulb being cut but the Guage still worked prior to changing the switch. Just for kicks, I hooked light back up and the Guage now works. But...the light pulses..which I am assuming that's why it was cut out. I don't know why or how it worked before.
I would like to find a wiring diagram for the dash and oil pressure switch circuit but have not had any luck.
Any help would be greatly appreciated!!

 

Have a look here. See if they have what you need.

 

Thanks HeyYou! that helps a bunch!