Can anyone tell me how to test gauge cluster using the RTE regulator?

[WH23G3G]

I'm having a problem with the temp and fuel gauge on my 65 Valiant. It has the RTE technologies solid state instrument voltage regulator in the back of the cluster. I think it cuts off power to the gauges if something is wrong The temp and fuel gauge were recored by Instrument Specialties Inc. The ammeter is new. I don't think I've ever had a working gauge in this car since I've had it for four years. Except the ammeter is NOS and the speedometer was redone and works good. The temp gauge worked fine at one point but something went wrong not sure I ever figured out what it was. So after I had the fuel and temp gauge recored the needles don't move at all when the ignition is on. If I put an original instrument voltage regulator in and turn the ignition on the gauges go full real quick. I also had a instrument voltage regulator converted to solid state by Instrument Specialties and it also makes the gauges go full. The engine/light harness and dash harness are about 2 years old now from Year One. Nothing's been cut or added to it. I did the test from the factory manual of probing the temp switch while engine running to see if the test light flashes but it doesn't. I was told by Instrument Specialties that the test wouldn't work anymore since it's been converted. It still didn't even light up the test light when I swapped in the old voltage regulator that made the gauges go full. I unplugged the temp switch wire and probed with a voltmeter with the ignition switch on and it barely showed a volt with either voltage regulator in. I unplugged the bulkhead connector on the back of the cluster and verified the wires were in the factory order which they are. I probed the instrument regulator with the voltmeter with the ignition on and it showed 11.65 volts, whether I had the RTE regulator in or the original one. I didn't know how to test the individual gauges with the voltmeter so I couldn't get anything from it. My battery is 12.40 volts. Is the RTE regulator working right since with it in the gauges don't move at all. But if I have the original plugged in the gauges go to full. I've been fighting this for over a year now. I got to be able to figure it out. The car is not nice enough to send to a shop for diagnosing but it runs and drives, but it's well worn.

[Pete in NH]

Hi,

These gauge systems are fairly simple, so it should be possible to find out what is wrong. Many A bodies had the instrument voltage regulator built into the fuel gauge and I'm pretty sure your 65 was one of them. So, I'm a bit puzzled by your description of the new plug in RTE solid state regulator. A picture of the back of the instrument cluster printed circuit board would be a big help to see what you actually have in there. When installing a solid state regulator the built in one must be disabled and this can be tricky.

One side of the gauge should have 5 volts from the instrument voltage regulator and the other side of the gauge goes to the sending unit, be it fuel or temperature. My first step would be to use a voltmeter and see if 5 volts is on one side of the gauge. Trouble shooting these systems takes a real voltmeter, a test light isn't good enough.

[b5blue]

You could try getting an extra temp sender, grounding it and heating it with a heat gun while attached to the senders wire as a field test.