Instrument Cluster not Working

[altayd9]

I'm having an issue on my 85 Grand Wagoneer where the Temperature, Fuel, and Oil Pressure gauges seem to not be working. I know of the CVR issue in the temperature gauge causing the others to stop working. I took the temperature gauge out to test it, a little metal circle fell out of the CVR assembly I think? I remember there being coiled wires and metal switch or something but I think but it seemed to be not making contact with that circle in it when I hooked up a 12V source. Afterwards when hooked up to a 12V source the gauge moved so I took that as it was working. Checked all the traces on the back of the board too and they were good. When I put it back in the car had the same problem, nothing changed. Do I have a broken CVR and does that mean I need to replace the whole temp gauge or is there something else I can do to get my dash working?

[altayd9]

I would have bought a new temp gauge but it seems there is no OEM option. BJ's only sells up to an 84 temp gauge and I've heard that maybe the CVR on those is different than the 85 so it's not compatible

[tgreese]

Do you have the old or new style gauge cluster? Some time in this era, the old cluster was replaced and the CVR was gone. Could be why the gauge does not apply to '85.

[tgreese]

The TSM (factory service manual) would tell you about the instruments - https://www.bjsoffroad.com/1984-87-Jeep ... _1056.html

There is an '89 TSM here https://oljeep.com/edge_parts_man.html which used the later type of of instrument panel. The earlier type would also be available with the '82 TSM on the same site. There were changes from year to year, so don't assume the other TSMs will be perfect authorities. Read the TSM - there will be tables and flow charts for diagnosis and repair of the instruments.

With anything electrical, you should use your multimeter (or maybe test light) and trace out the problem. Print out the wiring diagram and trace the problem through. You need the car in front of you to diagnose and repair the problem.

[altayd9]

Do you have the old or new style gauge cluster? Some time in this era, the old cluster was replaced and the CVR was gone. Could be why the gauge does not apply to '85.

It's the old style with round gauges that looks like the AMC Hornet cluster. I've been using the 82 TSM wiring diagrams to diagnose it, that's why I'm thinking CVR since the fuel and oil pressure gauges are wired through the Temperature gauge CVR

[tgreese]

If old style, be cautious applying 12V to the gauges. They won't survive long on a constant 12V battery voltage. Do not apply power to the cluster without connecting the cluster circuit board to ground - this will send constant 12V to the gauges and similarly burn them out.

Do you own a multimeter and know how to use it? Section 1L in the TSM covers this topic thoroughly. Look at 1L-46. Pin 11 connects to the ignition and provides power. This goes to pin 14 and is connected to pin 15 by the noise filter that pushes on to those pins. Power goes through the temperature gauge and comes out as (on average) 5V at A3 which both supplies the temperature gauge and the other gauges via the trace on the circuit board.

Realize that the factory CVR turns on-off to average to about 5V over time. Your multimeter may not be fast enough to keep up with the switching. A test light will show it.

The schematic is right there. Trace it out. Read the chapter.