Temp gauge not working

[adamsespico]

I have a 93 GMC Sonoma with a tbi 4.3l, auto trans, rwd. My temp gauge reads cold all the time & I've hooked it to my scan tool and the ecm temp sensor is working as it should and the hoses are getting warm so I know it's actually heating up. I've done some research but haven't been able to find a definite answer. Where is the temp sensor that sends signal to the gauge.

 

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[txab]

Cylinder head usually. Sometimes might be in intake near thermostat

[Jsdirt]

I believe on that vehicle it's on top near the t-stat. There's 2 on that one - one for the ECU, and one for the gauge.

 

The gauge one has one wire, ECU one has either 2 or 3 - I forget now. ECU one is in the head, driver's side.

[adamsespico]

Ok I've found a one wire sensor on the side of each head but they both look exactly the same. Same sensor, same connector, same wire color. The one on the passenger head is between 2&4 and the one on the driver's head is between 3&5. is there one temp sensor on each head???

 

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[Jsdirt]

Interesting. Quickest way to find out which is which is to grab a test light with the clip to ground, turn on the key, and stick the pointed end of the test light into the connector (don't jam it in there - just lightly touch it) - have someone watch the temp gauge.When you hit the correct one, the gauge will peg hot.

 

Test light is just added security that nothing can be damaged. Single wire ones you can just touch to the block to ground them, but I tell everyone to use a test light, just in case they ground the wrong wire.