I understand that the temp gauge should peg to the high end when the geen wire is grounded. What if it only goes to the middle? Is this a sure indication of a bad gauge? Have replaced the sending unit with one from Lectric Ltd. There is power to the back of the gauge but it will not register.

Thanks

 

The gauge should deflect full scale between grounded and open. so if it doesnt, I would think the gauge or wiring to it is bad.

 

I actually ran a jumper from the back of the gauge to the negative side of the battery. Also confirmed continuity on the green wire running from the gauge to the temp sending unit. Unless the radiator is bone dry, I don't know what else it could be.

 

make sure your really getting 12v from the battery to the guage, check with a voltmeter

 

what he said..

otherwise, could be a bad gauge.

 

Here's the procedure to diagnose temp gage problems:

Tests
A. Disconnect the green wire at the sending unit and turn on the ignition switch. The gauge hand should stay against the left side stop pin.

B.Ground the green wire disconnected from the sending unit. With the ignition switch still "ON," the gauge hand should swing across the dial to the right stop pin.

Corrective Measures
If the gauge hand does not stay to the left as in test "A", either the wire is grounded between the dash unit and the engine unit or the dash unit is defective.

Test further by disconnecting the dark green sending unit wire at the gauge. Turn on the ignition switch. If the gauge hand stays on the left hand stop pin, replace the disconnected wire. But, if the gauge hand still moves, replace the dash gauge.

If the gauge hand does not swing across the dial as in test "B", there is an open circuit in the wire between the sending unit and gauge, the gauge is defective, or current is not reaching the dash gauge.

Test further by grounding the sending unit terminal (dark green wire) of the dash gauge and turn "ON" the ignition switch. If the gauge hand now moves, replace the disconnected wire. If the gauge hand still does not move, connect a test lamp to a ground and to the power (pink wire) terminal of dash unit. If the lamp does not light, test the wire between the ignition switch and the dash unit by connecting a test lamp to the "Accessory" terminal at the ignition switch and to a ground. The test lamp should burn.

If the gauge hand operates correctly as in tests "A" and "B" but the gauge does not indicate temperature correctly, either the sending unit is defective or the dash gauge is out of calibration. Replace sending unit one of known accuracy. If gauge reading is still incorrect, replace dash unit.

If the gauge hand is at maximum at all times and test "A" and "B" indicate that the wiring and the dash unit are in condition, the sending unit is bad and needs replacement.

If the gauge hand will not move, the dash unit is bad, or incorrectly installed. Correct the installation or replace the gauge unit.

 

Kid. Is it possible to calibrate a gauge? I have not pulled the thing yet but sounds like it's enevitable. Only pulled the bezel back enough to access the back. I did confirm that there is a full 12 volts at the back.

Lot's of suppliers sell replacements. Has anyone found one to be better than the other?

Thanks again