New fuel gauge not working

[White_Lightning]

I’ve had problems with my fuel gauge constantly moving all over the place and sticking for a while, usually have to tap the gauge to get it to read correct. I have a new sending unit and went through the wiring to make sure everything was good and it was, made no difference. I’m assuming the gauge itself is the problem. I got a new gauge from LMC and just swapped the old one out and now I get no reading at all. Any suggestions?

 

[Goldie Driver]

Bad new gauge ? Not plugged in fully ? Wiring harness to the cluster not plugged in all the way ?

If you get lucky, one of the latter 2 ...

Oh, what happens if you put the old gauge back in now ?

Good luck !

Britt

 

[Vbb199]

Is the gauge grounded correctly? If you look on the back of the gauge and the thin circuit board there's usually a clearly marked - and +

Make sure somehow the one you got isn't backwards.

Is it pegged ?

Pegged full is a short on power side, pegged empty is a short on the ground side.

(I might have that backwards)

Thirdly, if its not pegged and just rests on Empty and the old one didn't work/got stuck, when you had the tank out, was there enough in there to register the float now?


And is the unit itself grounded? To the frame nearby?

 

[wlwarnke]

I believe the sensor is 0-90ohms (to ground)

0 ohms or shorted to ground reads empty.

90 ohms full

Open wire, sender ground wire bad read pegged full.

Have an ohm meter? Most trucks that I have seen had 2 sensor wires (just incase it had 2 tanks) connected to the gauge cluster. Measure those wires to ground. Should read between 0 and 90 ohms and be stable (if tank isn’t sloshing).

I have had the “spare wire” get shorted somewhere and cause issues. Just cut it off and leave the one that’s actually connected to the sender.

 

[Snoots]

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Sigh.