Instrument cluster testing

Sure is.

1..........Identify what problems you can before you start. Generally, this includes loose/ broken harness connector pins, contact finger connections for the IVR, and stud nut connections at the gauges. Loosen / tighten the stud nuts to scrub them. Do the same thing with all PC board to cluster ground screws.

2...........Attach a ground pigtail for your testing, but also later, to bolt to the dash frame or column support.

3...........Identify the proper harness connector pins for 12V in, and for each sender connection


4..........Go to RadShack (or order online, Mouser, Digikey, etc) some test resistors, or if you have the tank sender out and it works, and an accurate multimeter, you can use the tank sender

Get some resistors, at least 1/2 to 1 watt. You can parallel resistors to increase wattage. For example, for 1/2 scale, you can buy four 100 ohm, 1/2 watt and wire all 4 in parallel. This gives you a 25 ohm, 2 watt resistor.

For full scale (hot or full) you need 10-13 ohms, for 1/2 scale you need 23-25 ohms, and for the low end (cold or empty) you need 73--75 ohms.

You hook a test resistor from the appropriate sender connection to ground, you apply 12V to the proper pin, and wait a minute for the gauge to stabilize.

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Another thing you can do is to yank the IVR out and hook 3V (two flashlight cells in series) to the gauges directly. This should result in full scale reading, and both gauges should read the same. See the photo at the bottom of the page

If you look at the PC board, two of the gauge studs are hooked together. If you hook the battery to the two opposite studs of the two gauges, this results in about 1/8 scale

The top photo is with two gauge units in series across 3 volts, bottom is in parallel. Notice that both read the same

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If you have a ralley cluster, or an older car where the IVR is built inside the fuel gauge, this gets a bit more complicated. Notice that the fuel gauge has THREE terminals. One of these is the 12 "into" the IVR, one is the 5V out of the IVR going to the other gauges, and the third is the sender terminal for the fuel gauge.

For testing with a 3V battery you want to be certain you identify the two gauge terminals of the three