Fuel Gauge / Steering Column Question
My fuel gauge has never worked (stays at empty) and today I decided to tackle the issue.
I followed my TSM exactly using the following procedure:
1. Warm up engine - done
2. Check fuse - fuse ok
3. Observe temperature gauge - operating ok
4. Check for voltage at gauge input - voltage spikes present *see note*
5. Ground sender terminal of gauge - gauge did not move
The TSM at this point suggests to replace the gauge.
However I decided to do a little further troubleshooting and hooked a 12V source to one side of the gauge and grounded the other side. The needle quickly shot up to full and slowly drifted back down to empty when the voltage was removed. I know that the CVR normally only supplies 5V but this test at least shows that the gauge is mechanically sound.
*Note* - I get voltage spikes at the fuel gauge only when I bump the steering wheel back and forth or jiggle the turn signal. I also hear what sounds like a turn signal flasher click but the noise comes from a black cube that is in the wiring behind the dash (not silver and cylindrical and in the fuse panel). This clicking noise corresponds to the voltage spikes I'm seeing at the fuel gauge, so obviously something in the steering column or turn signal switch has a bad ground or is otherwise damaged.
I would think then that since I know I have intermittent power to the gauge, if I manually ground out the sender terminal of the gauge, that I would see the needle jump when I jiggle the turn signal and complete the circuit, but I am not.
To sum things up, when I supply external power and a confirmed ground to the gauge I get needle movement. When I hook things up properly (but using the same confirmed ground), I get voltage spikes from turn signal switch but no gauge movement.
On what is probably a related note, my horns are currently unplugged under the hood because when they are connected, turning the steering wheel or using the turn signal causes them to honk.
It really seems like I must have a short in the steering column but any clarification will be appreciated. Thanks.
1979 J10 360 TH400 QT