GMC 98 Vortec, temp sending unit resistance ranges

  • 1998 GMC

I have been having some problems with carbon build up and a faulty temperature sending unit.

I took the temp sensor out and tested it, I read 200 Ohms at around room temp, and then when I heated it up it went to about 1K ohms. It fluctuated and it was hard to get a constant reading. I have a dead temp sensor on the other half of the engine and it is dead, it reads 100 ohms when its hot and cold.

If my sensor is still good, then how come my gauge doesn't rise when the engine is warm?

I think the sensor is not within spec, but I don't know what the specs are for a temp. Unit for this engine, do you happen to know?

Do you
have the same problem?
Thursday, April 13th, 2006 AT 1:07 PM

1 Reply


There is one temperature sensor and it has two wires one yellow and the other brown or purple. The resistance sounds about right. The other one has one wire and is the gauge sending unit. If your temp isn't coming up it is probably the T-stat. Good luck

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Thursday, April 13th, 2006 AT 6:18 PM

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