Quote:
Originally Posted by Awann99
I’m trying to get the temp gauge working on my tach/vacuum cluster. It sits dead in the middle when the key is off or on. It will jump to the hot side and back to the middle when I start the truck. I pulled out the fuel wire from the fuse box and the temp gauge pinned at hot. I’ve tried grounding the green wire to the engine and the gauge doesn’t budge. The green wire doesn’t seem to have any breaks and it is connected firmly to the fuse Panel box from the engine bay to the cab. Is there a way to just bypass the gauge cluster and run the temp gauge separate?
Thanks.
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You need to do some more trouble shooting before condemning anything..
First - Gauge readings with the key OFF are meaningless.. There's no power applied to the gauges when the ignition is OFF.. I'm not sure why removing the fuel wire would affect the temp gauge?????
When the ignition switch is in the start position, it temporarily grounds the green wire. The gauge moving during the start engine cycle indicates gauge circuit is intact and working. Two issues come to mind. Either the calibration resistor on the back of the gauge is bad, or the sending unit is bad or the wrong type..
With the key on, disconnect the green wire at the sending unit, the gauge needle should move to full cold.. Ground the wire and the gauge needle should move to full hot.. Remove the sending unit. Rig up some jumper wires and connect a digital volt meter to the case and connector on the sending unit.. Place the sending unit in a pan of water and heat the pan on a stove.. As the water heats up, the resistance of the sending unit should change.. If it doesn't change or only changes a small amount, the sending unit is bad.....
If the sending unit passes these tests, you have to check the gauge.. Remove the cluster so you can get at the resistor. Remove the resistor from the gauge and test it with a DVM.. It should read somewhere around 85 - 90 ohms.. You cannot properly test the resistor while it's connected to the gauge.. Don't shortcut this step --- remove the resistor.. If the resistor tests good, the gauge itself is bad...