My stock '77 Trailduster with a 360 and A727 has a problem with the temp and fuel gauge not working. I put a new temp sensor on the intake and a new sending unit in the tank. The temp gauge doesn't register anything and the fuel gauge goes from an empty reading to a full reading regardless of how much fuel is in the tank. Does anyone know how I might troubleshoot this? Years ago I placed both the red and black leads on one of the posts essentially disengaging that gauge and not having any issues. I was thinking I might have a ground issue with the printed circuit board?? I live in Renton WA., just outside Seattle, if anyone knows of a place to buy new parts? It's now 4/21/2020 and when I place a test light probe on each post of the gauges, the light turns on meaning power is going to each stud when one should be grounded and the other one hot. Sure wish I new how to remove the dash board to make it easier to work on!!

 

I would pull the dash out and look for anything burnt or heating up. The amp gauges are notorious for doing this. Also check out the harness disconnect on the firewall for connectors with corrosion or heat damage. Check out the voltage regulator on the back of the dash for correct voltage. Last resort you will have to check the wiring running to the dash for any issues.
http://www.madelectrical.com/electri...p-gauges.shtml

 

So................electrical lol. Get a circuit tester, turn ignition on and test for voltage from ground to sender post, may need to poke thru the wire shield, to make sure you have power, same with the gas tank also. If no power check connections and fire wall plug. If light comes on but nothing still on the gauge, remove the wire on the sender and ground it. You can also use a jumper wire with alligator clips to ground without having to take it apart. if the gauge is good you should get full deflection you need a sender. If not behind the gauges you go. Again if voltage is present behind the gauge with the ignition on AND, might as well check sender power for voltage drops, it's the gauge. Older cars especially Mopars have a lot of issues with the fire wall plug. When I rewire mine, no more firewall plugs and electronic ignition! No more resisters LOL Good luck

 

Is there form of instruction that I can find that will help me in the dash removal? Thanks for your other tips. I did put a test light on both studs of each gauge. When I did that the test light lit up regardless of which stud I probed. Feel free to drop me a note or comments at timheffron@hotmail.com I live outside Seattle in a small town called Renton, (13 miles). Tim