1971 GMC temp gauge

[68gmsee]

Originally Posted by barrykathy

yes i think it is grounded do not see where it is picking it up?/ the cconnector on the back plane looks good ?? if i remove batt. the gauge goes back to normal as soon as i complete the ckt it peg's looks to me like a solid grd??

Disconnect it at the sending unit and see what happens. Sending unit can be in almost any location on the engine depending on which one you have or if someone has swapped engines in the past.

Turn the key on and see if gauge goes back to normal cold position with it disconnected. If it does, it's probably the sending unit gone bad. The sending unit is like a door to ground for the gauge. As the temp goes up it opens up more. If it's open all the way, the gauge is pegged on hot.