I am trying to figure out why my temp gauge doesn't work (reads cold all the time). To see if the brand new sender was the problem, I grounded the wire thinking the gauge would read full hot, but nothing happened. Is it supposed to read hot when grounded, which means I have a wiring or gauge problem? If so, any suggestions besides tracing the wire through the harness? Thanks, Joe

Use an ohmmeter (multimeter) to check the resistance of the sending unit. Mine reads hot all the time...but I just ignore it...

If you momentarily ground the sender wire (ignition switch on), the gauge should read full hot. If it doesn't, try running a est wire from the gauge directly to ground to rule out a bad wire or conection. If this checks out, you may well have a bad gauge.

I am having sender problems myself. I have hooked up two gauges and an aftermarket gauge and they all read low. My temp gun is indicating about 180 to 185 and I am only reading about 140. This just started happening recently. Can anyone give me an ohm reading when the car is cold on their sending unit. I have another sending unit and I am getting a different reading from both. It has different thread size than the one in the car.

Gordon, I responded to the thread you started. Joe, I'd have to agree you either have a wiring or gauge problem. I sent mine to this guy who did a great job calibrating my gauge to the sender. He also rebuilt my tach: VetteInstruments@aol.com/favicon.ico

It's the other way 'round. Ground the wire for cold, open the wire for hot...