Need pic or details on ground for factory fuel gage

[COCHEV]

I'm checking an annoying gage problem. The gas gage twitches all the time both when the engine is running or if the ignition is just on but not running. I can reach my hand through the stereo opening and mess with the printed circuit and sorta make it stop. I pulled it all out yesterday and found that one of the three prongs for the gage was in there cockeyed. Straightened that out and put it all together but that didn't fix it.

What I can't seem to figure out is how the gage or the printed circuit is grounded. From what I can tell there is some funky ground that ties into the top most pass side light gage bulb that runs over to the ash tray...

I read a few threads were guys have run their own ground to the fuel gage. I'd like to see/know how to do this. Here's a pic of my printed circuit

 

[blazerz]

that is a fiber optic that work's off the bulb to light up the ashtray.....it isn't very bright though.....

 

[TheBeast_88K5]

There are 2 ground paths in the printed circuit.
I hate those things... They always **** up.

With the connector installed, you can see where the paths lead.
It's more like your panel connector wiring, than the path.

 

[COCHEV]

There are 2 ground paths in the printed circuit.
I hate those things... They always **** up.

With the connector installed, you can see where the paths lead.
It's more like your panel connector wiring, than the path.

So the ground comes out of the main wire harness? What color and were does it ground? My manual leaves much to be desired

 

[COCHEV]

Further, its odd that only the gas gage that acts up. All the other gages are nice and steady

 

[TheBeast_88K5]

Your fuel gauge is standalone.
Your voltmeter is standalone.
Oil pressure is mech., Temp. is mech., and Speedo is mech.

It's not weird that its JUST the fuel gauge.
It's actually perfectly normal.

It gets weird when ALL of your gauges go wonky, and then return to normal... At random.


The grounds are black wires.
There was 2 grounds in mine.
One was pigtailed... (2 grounds spliced together.)

It should be obvious which ground is the fuel gage negative.
Stick the connector where it goes, and look.
It should go straight to the fuel gage negative.

I'm willing to bet that you have a couple gage lights that never come on, too...

 

[COCHEV]

Ugh, I just had the whole dash apart twice yesterday...

It wouldn't be these guys would it?

 

[4X4HIGH]

Ugh, I just had the whole dash apart twice yesterday...

It wouldn't be these guys would it?

Yep, that is the ground junction just behind the cluster on the A pillar.

 

[COCHEV]

So I removed that and sanded everything and reinstalled it. My gage now reads correctly (used to read a 1/4 less then what was in there) however the needle still dances around whenever the key is on, running or not....

 

[4X4HIGH]

So I removed that and sanded everything and reinstalled it. My gage now reads correctly (used to read a 1/4 less then what was in there) however the needle still dances around whenever the key is on, running or not....

Chase the wir from the gauge to the sender and look for any bare wiring or bad/kinked wiring and repair as needed. You may even want to run a NEW ground wire from the gauge to the ground junction.

 

[COCHEV]

Chase the wir from the gauge to the sender and look for any bare wiring or bad/kinked wiring and repair as needed. You may even want to run a NEW ground wire from the gauge to the ground junction.

I chased the wire from the tank up to were it disappears into a larger loom. Seemed OK , but I could redo that as well.

How do I run a new ground directly to the gage? Do I have to solder a wire to one of the three prongs on the back of the gage?

 

[dyeager535]

I don't think I'd waste my time running new wiring.

Trace the "signal" wire for the gauge, and for testing purposes, run a wire straight from the tank connector to the back of the gauge. Plug the cluster back in, and see if the problem is gone.

There is nothing fancy about the tank gauge wire, you can join a bunch of wires together to get enough length, just protect the splices from grounding.

I would expect the gauge to be garbage, the gauge is what "dampens" the reading of tank level. Otherwise the gauge display would follow every wave that is created when you turn, stop, start, go over a bump, etc.

You can also run a +, -, and the signal wire directly to the back of the gauge, if you want to eliminate the cluster circuit "board", again just for testing. That way you don't have to keep plugging and unplugging the instrument panel (IP) connector, which eventually causes problems with the copper connectors that it mates with.

 

[Blue85]

Your fuel gauge is standalone.
Your voltmeter is standalone.
Oil pressure is mech., Temp. is mech., and Speedo is mech.

ALL of the gauges are electrical, except the speedo/odo. Just look at the picture he posted for proof.

It looks like the gas gauge is sharing ground or power with lights or something else. I would try it with and without dash lights on, turn the dimmer, etc. to see if that has any effect. Then check for aftermarket stuff that is pulling from the dash light circuit (i.e. radio) to see if interferance comes from there. If you have an oscilloscope, put it on the fuel signal to see if it's really noisy.

But the gauge should not be able to move very quickly. These are air-core gauges with damped movement. Something may have come loose inside. Swapping in another gauge is quick once you get your hands on one.

 

[big dan]

ALL of the gauges are electrical, except the speedo/odo. Just look at the picture he posted for proof.

x2, dont recall ever seeing factory mech. oil pressure or water temp gauges on these trucks.