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The 'good' news is that none of the gauges in my '72 Camper Special work, so maybe it's a problem common to all of them. Well, the speedo works, but that's mechanical. The oil, temp, and gas gauges don't do anything. I've had the cluster out, and it *looks* OK. The connector plug-in looks good. No fuses blown. So- how do I track down what's going on? I checked for voltage at the gas sending unit and got nothing. If it's reading resistance to ground, it wouldn't, though (I think). How do these gauges work? How do you go about troubleshooting? I'm not against going to aftermarket gauges, if it comes down to that. Can't drive Bubba until I can get some gauges working- at least the gas gauge. The wiring in this truck is pretty bad, so I'm not averse to running new wires, if I could figure out how to connect them. Thanks for any help!
You need to change your Instrument Cluster Voltage Regulator (ICVR) on the back of the cluster.
I agree. The voltage regulator plugs in to the printed circuit on the back of the cluster like a 9 volt battery. Also, check the fuses. I'm a 73-79 guy, so I can't tell you which fuse powers the ICVR that powers the gauges.
The regulator looks like a small aspirin box with 2 wires connected with a spade terminal. It gets 12 volts when the ignition is on. With an ohm meter test each wire on low scale that goes to it’s respective sending unit. There should be a resistance reading that will vary depending on the sender it connects to. The most important thing to check for is a short to ground, one of the wires may have the insulation worn off. If one of the wires is shorted to ground it will burn out the regulator. Usually the wire going to the fuel sender is the culprit.
IMO, You should test and diagnose the issue before blindly buying a new regulator. Check for 12v going into the regulator and that it is grounded. Then verify that something around 4-7v coming out. Then check that the output voltage makes it out of the cluster connector... and so on.