04 Chevy Tahoe, 4.8L Eng Oil Pressure Pegged all the time…

04 chev Tahoe, 131.5k miles. 4.8L Eng.

Oil pressure sending unit pegged just under 80 psi all the time. When I turn the key on and off without starting the vehicle it goes up to just under 80 psi and stays there until the vehicle is shut off or if the vehicle isn’t running until the key is turned off. Using by directional control with the scan tool where you can operate all of the dash cluster gauge is it cycles down and goes back up once communication with cluster stops. 

I have a copy of the wiring description just need to make sure I don’t fry the computer. 

I have a sensor simulator I’ve picked up from AES wave recently that I need to sit down and learn but it can wait unless someone has used one and can tell me a quick and easy set up procedure that they’re aware of. Otherwise I have test light, power probe as I’m sure one of them can get it done?



 


 

Sensor is bad check for oil in the connector. If oil is in the connector then clean connector and replace sensor. I just did this to my truck with a 5.3. scan data should say 134 psi if sensor failed
 

Monitored is 129.95 & displayed is 147.94 with a low of 11.6 for both. Maybe I’ll just try to throw my manual gauge on and see what it says just so I can know I did. Lol…. I have a ac delco one. Glad I got it as saw a guy on YouTube lsxmatt that replaced with a autozone and few months later was leaking. Yeah it was lifetime warrantied but I get pretty much any part I buy warrantied including……. Yes windshield wiper blades…… yeah really I do. Just give them the old one back and a new one leaves with me without package…. 


Thanks! 

This is just a typical 3-wire pressure sensor.
Testing should first be voltage readings on all 3 wires, plugged in and backprobing KOEO, then start it and build oil psi and check it again.
Then, if the sensor signal proves to be fixed and never moves, if you want to simulate a change, just do the opposite of what you see. If the signal is stuck high, drive it low, if it is stuck low, drive it high. Use your incandescent test light for the tests.
If the signal is high (5v), connect the light to ground and pull it down
If the signal is low (0v) connect your test light to the 5v ref wire and signal wire using the test light as a jumper.
These last two tests are done with the sensor unplugged. Watch your gauge for a response

Late to the party. :blush:

The pressure PIDs are in the instrument cluster, but the voltage PID is in the ECM, correct? With the sensor plugged in, KOEO, what's your voltage? 4.5V or higher, probably.

Unplugged, voltage should go to zero. If it does, I'd go direct for a sensor. :silly: BUT, if you want to be correct about it, you should verify sensor ground to make double sure. The problem is, this sensor lives behind the intake, and it isn't the easiest to get to. Just unplugging it can be work if you're not familiar.

I went through this thought process in another thread:

www.scannerdanner.com/forum/diagnostic-t...xt-easiest-step.html