MN71W30

My 71 442 needed a new fuse box and I ran across a 72 harness. My 71 has factory gauges with a tach. The 72 was a standard car. I used my old harness under the hood and converted the 72 harness to work with my existing under the hood harness, it took some time.

I have dash lights, starter, cig lighter, gen light. The problem I have is when I touch the temp wire to ground the gauge reads hot, I think that is correct. I touch the oil gauge sending unit wire to ground and it goes to low. So when the key is on the guage reads backwards, max pressure without it running . Could my sending unit be bad? I turned it over and it seemed to work. I have a mechanical gauge hooked up also to verify pressure. The gauges are fed with one wire and they branch out so I don't think I could have it hooked up wrong.
Thanks for any help,
Dave

Lady72nRob71

Yes, grounding the temp terminal (green) will cause the gauge to read hot.

Grounding the oil terminal (dark blue) will cause the gauge to read low. Having it open will make the oil gauge read high. Since you verified pressure, it is possible your sender is bad. Mine did this once - a new borg-warner sending unit. I lightly tapped it on the side with a screwdriver and it worked again. Yours may just need replacing.
NOW What did you turn over?? If the engine, what did the gauge read?

Did you disconnect the green temp wire from the ignition switch? If not, your temp gauge will peg hot when cranking the engine. That was a bulb test function for the idiot light.

If this is the only problem you encountered rewiring a whole car, than you are doing great!