Jerry,
I'm assuming electric gauges here....
If you have a simple volt meter, make a few simple checks.
1. First step is to measure the voltage at the
oil temp sensor. Should indicate "something", but not ZERO volts. (ignition switch ON)
2. If you have a voltage reading, have an assistant watch the gauge closely while you short the sensor wire to ground.
Short it and un-short it as quick as possible, you will damage the gauge if left shorted too long. If the gauge needle moved, replace the sensor.
3. If you had zero volts in step one, your going to have to get to the back of the dash to check the connections on the gauge.
4. On the back of the gauge, there are two terminals. One is usually labled '1' or '+' and should measure 12 volts with the ignition switch on. The other terminal is usually labled 'S' and connects to the sensor. Measure the voltage at the 'S' terminal, it should show something.
5. Tests results...
If you didn't measure voltage at the 1 or + terminal, you need to repair the wire from the gauge to the ignition switch.
If you didn't measure voltage at the S terminal, but did at the 1 or + terminal, the gauge is bad.
If you measured voltage at both the 1 or + terminal and the S terminal, but didn't at the sensor (step one) then repair the wire between the gauge and the sensor.
Happy trouble shooting
- Jim -