I have a 99 Suburban, 5.7, 4 wheel drive, LT model. It had a blown engine when I bought it. I built a 40 over engine that runs good. Everything works except oil gage. I changed sending unit and it reads pressure from 80 lbs, not zero. How do I get it to read pressure from zero, not 80? When you turn the key off, pressure comes back to 80. I had cranked engine with old gage, which also read from 80 lbs. Thinking it was the sending unit, I bought a new sending unit. Still have same problem.


The other gauges seem to work okay. Gas gauge just above oil gage has needle shake, but it seems to read fuel level okay.

 

Possibly a short in the wiring to and from the gauge.