water temp gague not working

[freddiedad]

Engine overheated now temp gague not working . How can I find out if it's the themosat or the sending unit? omc, gmc v6, 3.8 liter.

Thanks Steve

 

[chiefalen]

Did you use a tester to see if you have power to the gauge ? lay on your back under the dash, all the wires good, not green, whats going on under the dash ?

 

[boatin_bob]

Is the gauge at the left (cold) or at the right (hot)? A quick test of the gauge is to take a jumper wire and touch one end to the top of the sender (normally a tan wire) and the other end to ground (somewhere on the block) with the key on, this should cause the gauge to peg all the way over to the hot side, if it doesn't then you have to make sure the gauge has 12v on the back and then you can ground out the (S) sender terminal to verify the wiring is OK or if the gauge is bad.