Coolant temperature gauge does not work


Captain Tenneal
Supporting Member
Dec 26, 2013
Light green is for the gauge, and grounds through the sensor.
Idiot is dark green and grounds through the sensor as well.

Oopsie. had light green twice, but if you looked at the diagram, you could figure it out.
Last edited:


Mar 31, 2006
Kitchener, Ontario

cold snow GIF by funk
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Thread starter
Oct 20, 2020
Is there another location for a sensor besides the one near the water neck? My car doesn't have an ecu if that matters


Dec 28, 2020
Someone else asked a similar question recently. It seems to me that someone else remarked that there are two different sender units, one that gives info to the ECM, and one that goes to the gauge. The single blade sender should screw into the side of the head, either between 1& 3 on the driver side, or 6 & 8 on the passenger side, depending on your wiring harness (oops, forgot that you have the v6, but should still be in the head).
Search other threads for a more definitive answer.
The two wire style is mounted at/near the water neck.
That was my post (Temp Light on Dash), where I show pictures of the temp switch for the ECM and connector. My ECM is located over on the passenger front fender well. Good luck. I have a different issue, where I see the single blade temp sensor coming out of the front passenger side of the engine, but can't seem to find the wire to connect it to. My temp dummy gage light inside the care pulses, never off or never fully displayed.


Thread starter
Oct 20, 2020
Kind of sounds like that wire is loose/exposed tucked away somewhere, shorting against a ground causing the light to flicker on and off. Mine is a green or green/white wire going to that sensor.
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G-Body Guru
Feb 20, 2018
For a SBC the sensor tends to be a single wire unit that gets screwed into the head between 1 and 3 on the DR side or 6 and 8 on the PASS side. Since the heads are interchangeable side to side, the location is the same, just designated differently depending on what bank of the engine that head is bolted to.

The connection showing in the picture is a two pin GM specific connector that has a fancy name that eludes me right now. it is not weatherpak or Deutsch, the pins are flat and very thin or narrow; think the term is "metripak".

As noted above for a side mounted sending unit, the wire is a dark green and will have a spade female end on it enclosed in a plastic housing. it is perfectly possible that the connections rusted out due to corrosion between the wire and the terminal and the wire is just hanging in the wind, tucked away under something or wound back on itself and taped off.

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