How to test a tempreature gagu

[jbgroby]

How to test a temperature gauge

I’ve taken my truck for several runs around the block to break it in warm it up and all the gauges work except the temp gauge. Because the temp sending unit and thermostat are about 6 yrs. old and have been sitting for, was wondering if they went bad? I can buy replacements Saturday and make a switch, but was also wondering if the temp gauge may be bad.

All other gauges are and lights are working, I have a common power and ground to all gauges, so the ground is ok (first thing I thought of). Is there a way to test the gauge before I pull off the other parts for replacements?

According to the GMC BB, there are 3 different temp. thermostat that can work with the truck (305 V-6)

160 deg Stant 13006
180 deg Stant 13008
195 deg Stant 13009 (OE temp)

The list that was found by AZ Ken from the BB said OE was 195. he didn’t know if that was accurate. The 160 and the 180 are listed as "alternate". This is a designation used for older vehicles like ours and is safe to use. Thermostats do not fully open until about 15 deg above rated. He suggested that I use the 180 and see what the temp gauge reads and if the cap works properly.

Does the cap and therm need to be close?