Voltage Guage?

[68longhorn]

I took my 86swb dash apart to do some diag and some led upgrades. My voltage guage is always pointed to the left, less than 8 volts. I applied direct voltage and ground to the 2 contacts on the back of my guage and it still doesn't move, i assume that means the guage is bad, is that correct? While the cluster is apart is there anything i should do before reassembly?

[ray_mcavoy]

There is a resistor mounted directly on the back of the voltmeter. It's the rectangular piece of white ceramic with the blue paint as seen in this photo:



If that resistor is burned out or simply not making good contact with the terminals on the gauge, the needle will not move.

You can do some additional testing with an ohmmeter (multimeter set to measure resistance). Measuring between the terminals I marked A and C in the above photo should give a reading near 127Ω if the resistor is good. Measuring between terminals B and C should give a reading near 122Ω if the internal voltmeter coil is good.

Finally, when you apply 12V directly to the gauge for testing purposes, the +12V connection should go to terminal A and ground should go to terminal B (make no external connections to terminal C).