temp gauge pegging out?

[76 bronco J]

,,,,for testing the instrument voltage regulator....best to leave it in place to begin testing,,,,first disconnect the wire from the temp. sending unit,, connect the lead of a test light or positive lead of the voltmeter to the wire removed from the sending unit then the other lead to good ground,,,,with the ignition switch in the ON or ACC position, a flashing light or fluctuating voltage will indicate that the instrument voltage regulator is operating and the gauge circuit is not interrupted,,,,if the light stays on the or the voltage is steady,replace the I.R.V.,,,if no voltage is indicated check for a open circuit in the I.R.V.,gauge windings or the printed circuit<<< usually this all checks out for me atleast & I end up just replacing the cheap sending unit(under $10) & all is well.....little side note says>> do not ground or spark either terminal of the IRV as this will damage the dash wiring harness or the IRV itself,,,,,it say also a pulsating voltage shown but the the gauge is not acurate to perform a calibration test,,,,,>>>before doing these tests >>>I would take the thermostat back out the engine then place on a stove in some water while using a cooking thermometer to verify pretty close to what temp it is opening at, I do this to all of them before installing to avoid guessing

 

[Burchtree]

It appears that I'll need a new VR. The local shop is getting one in today.

Here is a random picture of it apart - love those wires that go nowhere. ?:? ;D