Temp gauge quit.

[N2Clsx]

The wire from the temp gauge popped off of the sensor and set on the header for a day or so and the temp gauge was pinned to hot even with the key not in the truck. Well we moved the wire back to the sensor and the gauge went back to normal but now we get no reading at all. Could we have fried the temp gauge? Any advice?

Thanks, Ray

[N2Clsx]

Nobody?

[MagmaJct]

I have a few thoughts that I will share:

Measure the resistance of the sensor at various engine temps. (i.e. when cold, when hot.) It's not likely the sensor is damaged since a missing wire shouldn't fry that, but at least it can be eliminated.

Is the thermostat opening? When I first got my truck I found my temp gauge didn't work. I got a new sensor from Checker that didn't fit. (They insisted it was the right sensor!) Turns out my Uncle when he owned it, replaced the stock 195F thermostat with a 165F which kept the engine too cold to move the needle.

The odds are some damage was done to the gauge. Unfortunately I don't know how the gauge converts the sensor resistance to a needle movement. I'm thinking it would use a simple voltage divider using a resistor but again you would get no reading at all.

Is it possible the wire was damaged when it was disconnected, maybe under a sleeve or something?

[cdowns]

take wire off sender and ground the wire to the engine// that should cause gauge to peg at the max// if not then you either have a brokem wire or a bad gauge

[N2Clsx]

Originally Posted by cdowns

take wire off sender and ground the wire to the engine// that should cause gauge to peg at the max// if not then you either have a brokem wire or a bad gauge

Thats exactly what happened. My son called to tell me that his temp gauge was pinned to hot and the engine wasnt running. I told him to drive it home and we will take a look. Well we found the tip resting on the header. We put it back on the sensor and have not got a reading since.

[imdarren]

Copper wire is a great heat transmitter.
Possibility -
The terminal resting on the header sent heat up the wire and could have melted the insulation at another point align the wire. If the wire is grounded out somewhere, the gauge will stick at hot. Inspect the wire up further and make sure it's ok, not melted, and not grounded out.

Darren

[N2Clsx]

Originally Posted by imdarren

Copper wire is a great heat transmitter.
Possibility -
The terminal resting on the header sent heat up the wire and could have melted the insulation at another point align the wire. If the wire is grounded out somewhere, the gauge will stick at hot. Inspect the wire up further and make sure it's ok, not melted, and not grounded out.

Darren

Sorry that I was not clear. I removed the wire from the header and put it back on the sensor and the temp gauge went back to 0. Now when the truck gets warm we get no reading.