koondawg_74 roadrunner

So finally have the gauges back in the roadrunner. I want to get the original gauges hooked up even though I have a 3 gauge aftermarket set. So there was no power going to the voltage limiter and I got that hooked up like it should be. Everything is hooked up.
Now the fuel gauge is reading completely full ( key on) when it has maybe an eighth of a tank. It has a new sending unit and a good ground wire connected. So I took the wire off and the gauge doesn't read. Then all of a sudden my temperature gauge decides it wants to go all the way to hot, when I'm not even running! Again with the temperature wire unhooked it doesn't read. Not sure if the alt gauge works because it never drains. The oil pressure works but not good at all. My service manual says take take a voltmeter and touch the temp wire and ground and if it is fluctuating then the limiter is good (with key on), but it moves and stays in one spot. I also stuck my other voltage limiter off of another cluster in there and same thing. Any ideas?! Any help is very appreciated!

bremereric

Maybe not a good ground. I know the cluster has to be well grounded.

koondawg_74 roadrunner

I attached alligator leads to a good ground to the voltage limiter and that didn't do it. Where else would it need to be grounded?

440roadrunner

These clusters can have multiple problems You need to consider the gauges as a complete end - to - end SYSTEM and check it out completely

My 67 Dart was a great example of multi-problems.

Make absolutely sure the harness connector is delivering solid 12V from the key to the PC board. The connector pins can be loose/ corroded.

On my Dart, the brass fingers that form the contacts/ socket for the VR were not making contact with the PC board traces. I had to solder jumper wires from the contact fingers to the board

The VR itself was not working correctly

The studs for the guages, and the "fake" speed nuts were not making contact. Replace them with real nuts, and tighten/ loosen/ tighten them to scrub the connection clean

Then actually test the gauges. You can hook test resistances from the sender connection of the cluster to ground The test resistances for all three gauges are:

L = 73.7 Ohms (empty)
M = 23.0 Ohms (1/2)
H = 10.2 Ohms (full)

If you do nothing else, "rig" the 1/2 scale resistance by going to radio shack and buying 4 100 ohm, 1/2 watt resistors, and wire all 4 in parallel. This will give you 25 ohms, for testing 1/2 scale.

You need 12V to the "ignition" feed, ground, and this resistor from the gauge sender stud to ground. Give it about a minute to stabilize.

You can also check in the car by simply hooking the resistance from the disconnected sender wire to ground.

koondawg_74 roadrunner

Took the sending wires off of the temp and fuel senders. Grounded each one and turned the key on. Both went to full. With the wires off of the fuel sending unit, the sender reads 4 or 5 ohms and I know it is close to empty. It is a brand new sending unit. I also got under the dash with a test light and touched all the fingers on the voltage limiter and the light lit up. Also on the gauges. When I touch the temp sender with the test light, the light lit up but did not flash like I think it's supposed to?