Temp gauge issue

[ScottH]

Truck is a 66 c10 with factory gauges (not idiot lights) with original 327 engine. When nothing is turned on the temp gauge reads almost on H, pointer is just at end of green line. When ignition is turn on the needle jumps right to the C. When running the needle never moves.

If I ground the sender wire, the needle jumps past the H.

I'm guessing the sending unit needs to be replaced, but wasn't sure if the action of the needle would be correct if this is the case.

Any info is appreciated.

Thanks

[The Rocknrod]

The sender is just a variable ground. Turn the key on, ground the sender wire to something and see if the gauge moves. This should rule out all except the sender. Make sure your gauge panel is also grounded.
If the sender is bad you must use the temp sender that is correct for your year truck with a gauge. Lectric Limited sells the "correct" units - https://www.lectriclimited.com/

[ScottH]

thanks

[roll_the_dice]

I just got my lectric limited sending unit delivered yesterday. I hope to get it swapped out this weekend. Mine was pegged at H at normal operating temp...I also have a digital readout and it was not running Hot...so I hope this rectifies the gauge.