Apparently I didn't check fuel this morning and probably because it was "operating" yesterday. However, after verifying that the fuel sending unit is operating just fine from 4.3 Ohm to 124.0 Ohm I checked the gauges again with the test lamp. Oil and Temp work just fine, nice and smooth. The ammeter does nothing. So I took the face off and removed the gauges. On the attached photos you can see that the bulb is lit and is brighter on the center post than the side post but there is no needle movement. I used a matchbook emery between the points to no avail. I note that the two "stacks" of finely wound wire are white, however, the stack on the near side in the photo (opposite of the points) has some brownish coloration and I am "presuming" that means I cooked it yesterday while the motor was running, it was pegged to full and I was checking other stuff. The ammeter is very simple but it doesn't do anything. Not sure what to check on it. There are a couple of wings on either side of the needle arm, they were crooked and I'm not sure if there is a specified air gap between them and the magnet. Bending them closer didn't do anything. So I think that the only thing to do is rip this harness out and see if I can make heads or tails about how it has been rewired or partly rewired. It has a non-stock fuse box as it has the blade fuses and as I mentioned before there is nothing like a color code. Although I did find the correct wire at the fuel sending unit, but it was only about twelve inches and then spliced into a blue wire that checks to the dashboard, but it is a different color (black of course) when it gets to the dash and so I'm not sure where it changed, again. Frustrating to say the least. There is just so much jury rigging that went on with this vehicle. I'm $15K, six months and still can't take it back to inspection. Not my best decision.
So the OIL and TEMP gauges are OK.
The AMP gauges is difficult to test. It takes 1 to 3 Amps before you see the needle moving. That AMP meter is a magnetometer with a fixed and a moving magnet. When the current changes, the magnetic field changes which will make the needle move. Don't start bending or adjusting. It will work fine once it is hooked up.
You can do an ohm test. The reading should be 0 (zero) Ω / ohm as if it is a short (which it is).
Now the FUEL gauge.... This is a 2 in 1 unit.
1st part is the Voltage Regulator and the 2nd part is the FUEL gauge. You can not test this with a test light in series.
I hope you've read my postings earlier in this thread to understand what this gauge does. Go to page 2 / #27
For your convenience I post 2 more pics to show how they are build.
This is the FUEL gauge seen from the front when you remove the face plate.
This is the FUEL gauge seen from the back.
To test this gauge you have to connect Pos. and Neg. 12V to the gauge. Once you've hooked this up you'll notice that the VR arm (stack as you call it) is moving in a rapid way, about 2x per second. It's now creating an intermittent 0 - 12 - 0 - 12 - 0 - 12V.
Effective this is a wobbly 6 Volt. This Voltage is internally connected to the FUEL gauge and to the top stud which goes to the TEMP gauge.
When you have this working, hook up your test light to the SENDER stud and the ground (neg.) folded lip. The test light should flash and the needle should move.
I hope you didn't fry this gauge.
For the wiring to the senders......
Just leave the old wires and run new ones directly from the senders to the cluster.
BTW, make sure that your fuel sender is grounded.
(pic thanks to mud member fj718)
Rudi
