willysmjeeps.com

Trying to troubleshoot two of my gages.

For the oil pressure gage, with the wire disconnected, the side going to the sending unit should be isolated and not be grounded through the case, correct?

The water temp gage has 24 volts reaching it, had a good wire to the sending unit, but fails to perform like the troubleshooting guide says. Is there another test I can perform on it?

Don't shotgun troubleshoot your gauge systems. Use the tech bulletin that walks you through it step by step, answers all your questions and gives you all the specs without loosing any accuracy in the transmission across the internet.

Army TB 9-2300-228-20 Tactical Transport and Combat Vehicles: Troubleshooting for Instrument Cluster Gages, Switches, Circuit Breakers, Sending Units and Related Wiring dated 8 July 1960.

http://www.cj3a.info/sibling/milgauge/milgage.htm

Sorry, my post was a bit incomplete.

I was working through the gage troubleshooting manual.

After the oil press gage kept failing each test, I finally checked the ports on back with no cables attached.

Using a multimeter, the one that would go to the sending unit appeared to be grounded through the case.

I was asking if that connection shouldn't be isolated from the case?

The gauges all have two grounds. One thru the case and one thru the sender. If you remove the lead from the sender and connect the ohm meter to it and touch the other test lead to the dash, frame. tub or gauge case you will show continuity if all is correct since both share the same ground. I assume you are doing test "G" and instead of touching the left probe in the illustration below to the vehicle's tub you are touching it to the gauge case. As you can see in the illustration both are grounded to the jeep. If on the otherhand you have the ohm meter connected to the gauge case and the gauge's sender terminal on the back of the gauge then you should not have continuity.

Thanks Wes!

The situation is like your last statement. The sender terminal on the gauge and the gauge case have continuity.

Are there any serviceable parts on the gauge itself, like a rubber insulator, that may have cracked and broken on that terminal?

The gauges are only serviceable through the rolled bezel on their face. There are tools made for uncrimping these bezels and then roll crimping them back on but there is no published data available for internal repair guidance. Their innards are extremely sensitive. At a price running in the $40 range it's hard to justify several hours of repair work.