Need help please
 

Im hoping to get a hint or solution to my oil pressure gauge problem.
i have a 97 gmc jimmy 4x4, all fresh rebuild. On the instrument cluster, 10v dc is present at pin 7 and also on the test points. Yet, the gauge reads maxed out with each cluster ive tried.
please help or at least guide me.
Im wanting to drive it, but not w/out that gauge working.. thanks

Have you tried measuring the oils pressure sender output from engine off to idle and verify the sender output (at the IPC connector? How about checking the sender wire (resistance, short to gnd, short to power)? The '97 circuit looks to be an old school resistive sender and a simple oil pressure gauge. Constant high reading at the gauge should be infinite resistance which implies a wiring problem. You can verify the gauge operation by using a fused jumper to ground on IPC pin 7 . The gauge should go to zero


George

will ground it using a fused jumper 1st thing in the morning, and thanks. The sensor is putting out 10v

The sensor is a just variable resistor which cannot generate a voltage. Are you measuring 10V on the wire from the sender with it unplugged from the IP?

George

Reading 10v on pin 7 at cluster connection and also on test pins on cluster. Reversing leads on my fluke, polarity changes

With the sending unit attached or is pin 7 on the IPC open?


George

Oil pressure sensor is installed.
IPC is connected.
Pin 7 from dash harness to cluster.
Reads 10v dc..
On the back of the instrument cluster are test points. Grd, ign, oil, tach, etc.
Im getting 10v dc on the oil pin to grd pin and changes polarity w/lead reversal..
Headed to the shop shortly to give that fused ground shot a try.

I have 3 instrument clusters, all peg out oil gauge with key

ok that’s more clear. The voltage on that pin only verifies power to the IPC and through the oil pressure gauge to the connector. I suspect the sending unit or it’s wire. The sending unit acts as a variable resistor which varies the current through the circuit.

The other test to perform is to see if the sending unit and it’s wire are functioning correctly. Unplug the connector and measure the resistance from the oil pressure sending unit wire at the unplugged IPC connector to battery ground once with engine off and again at idle. I don’t know the specs on that sender but you should get zero or single digit ohms at idle and tens of ohms at idle like around 50.


George

Headed to parts hse, gonna replace the new oil pressure sensor. Will contact u soon.
thanx for the help and patience.

You should diagnose the wire from the pressure sensor to the IPC first, Resistance while open at both ends, short to ground and short to power.


George