'65 mustang with 39,000 miles. When I turn my ignition on, The temperature gauge shows “HOT” all the way to the right even when the motor is cold. I replaced the sending unit and checked the wire for a short (no short) and it still shows HOT. How do I test the dash temperature gauge or should I replace it… Your year range did not go down to “65” so I chose “70.”
Pull the gauge cluster, disconnect the temp gauge and probe the sender wires. I’d bet you really do have a short. Should be a 12v, ground and signal wire. Check the signal and 12v for voltage with the key on and the ground for continuity to ground. If you see 12v on the signal, you have a short. If you don’t, it is the gauge.
If the wiring harness has never been changed, it is likely junk. You can buy reproduction harnesses for a 65 Stang.
THANKS! I’LL try it
You might want to read this…
It explains the 6 volt nature of the gauges, rather than 12 volt (my bad) and what colors the wires are as well as the wiring diagram.