91 GMC Vandura Van - Temp Guage stopped working


Old 07-01-02, 12:15 PM
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91 GMC Vandura Van - Temp Guage stopped working

My GMC Van (2500 350 5.7 liter) overheated sometime back. I replaced the Thermostat and a few days later the Temp Guage stopped working. I replaced the Engine coolant temp sender on top of the engine next to the Thermostat and it did not fix the problem. I checked and I have power to the sender. I have power at the Temp guage. I have a yellow and black wire on the sender and Drk Green wire on the Temp Guage. The Hayes manual says the Temp guage's Drk Green wire goes directly the the Temp Sender. The Temp sender on the engine has yellow and black wires. Do I have another temp sender that I'm not seeing? Or do the Drk Green and yellow wires connect somewhere that I'm not seeing? Could my Temp Guage be fried and if so how do I test it?
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Old 07-01-02, 05:31 PM
Join Date: Dec 2001
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the temp sender will be on the cylinder head either between #1 and #3 plugs on the drivers side or between #6 and #8 plugs on the passenger side.
Old 07-01-02, 05:34 PM
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Check for another sender unit. The one you replaced was probably for the computer. Check on the side of the block (left side if it's like the 350 Chevy in my wrecker). You can check the circuit by pulling the wire off the sender and grounding it with the key on; the temp gauge should go all the way to the "peg" at Hot.
If the gauge stays all the way to cold you have a wiring or gauge problem.
Old 07-01-02, 05:47 PM
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The yellow and black wires are for the temperature coolant sensor for the ECM. That's not what you want.

As correctly pointed out you want the SENDING unit. It's where Bejay said. That should do the trick.

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