1987 J10 oil gauge reads high--60-80psi

[rocklaurence]

OK, this issue started with a bad battery connection/or ground when cranking. While cranking the motor for start the Oil and Battery gauges pegged and were stuck at the top. I fixed the cranking issue and have run with the bad gauges for a couple years now. However, I recently got off my Tired Butt and replaced the gauge cluster. The Battery now reads accurately but the oil gauge reads 0-with ignition off; 60psi with ignition on and 80 psi when the engine is running. So, is the sender shot or is there some kind of resistor or is there a bad ground in the harness? I have a mechanical gauge and the pressure is around 30-45psi

[440sixpack]

I'm not sure about an 87 but normally there is a voltage limiter on the cluster. if this goes bad most of the time nothing works but I suppose it could stick in the full 12v mode which will fry the gauges.

Does your fuel and temp gauge work ok ? if so then I'd suspect the sender first and then the gauge itself.

[rocklaurence]

I replace the whole cluster of gauges and everything works except the Oil.

[letank]

The 87 is a different beast. Check oljeep site for troubleshooting. IIRC, the senders are reversed resistance, so you need the right year senders.

[babywag]

On late model,high oil gauge reading is a poor connection/high resistance will = high reading.
A pegged gauge would indicate no connection.

Often the connector on sending unit wire is trashed, snip it off and replace it.
If still no bueno, check wire for damage, then replace the sender last.

[rocklaurence]

Problem resolved! Previously, I had a different version/year instrument cluster and had to add 70ohms of resistance to the signal wire to make it read correctly. I forgot that I put those in..... I removed the risistors and now it reads correctly. Yay!

[az chip]

Resistance is futile....ohm...