Fuel gauge question #355

[jdl71]

Originally Posted by ray_mcavoy

Four things that can cause the fuel gauge to stay on empty include:

(1) Bad sending unit.
(2) Short to ground in the gauge to sending unit wire.
(3) Bad ground connection at the gauge.
(4) Bad gauge (open "full" coil).

It sounds like you've already ruled out #1 & #2. But just to be sure, you might want to try hooking up the gauges outside of the truck just to be sure. To do that, simply hook the gauge's power terminal (pink wire) to the positive terminal of a 12V battery or 12VDC power supply. And connect the negative side of the battery or power supply to the metal cluster case. Don't connect anything to the gauge's sending unit terminal.

If that makes the gauge swing to full (or beyond), you know the gauge is good. But if it continues to stay on empty, take the gauge out of the cluster and hook the battery or power supply negative terminal directly to the gauge's ground point. If I remember correctly, that's basically just a contact on the back of the gauge that touches the metal cluster housing for it's ground connection. And if that makes the gauge work, check for tarnish/corrosion where the gauge mounts to the cluster tin. If not, it's most likely a bad gauge.

I think I can also rule out #3 as the other gauges work as do the dash lights, unless you are meaning the ground connection on the gauge itself, which you might. I’m fairly certain the dash is grounded.

I also have swapped clusters with one I had of unknown condition and tried to get the gauge I took out to work on the bench, but am going to try again using your instructions in regards to the ground on the gauge itself. Another post I read said that the gauge itself is almost never the issue but I am almost certain I have ruled everything else out. Thank you for the suggestions.