Sending Unit / Fuel Gauge Issues

[JohnTrotto]

A while back my fuel gauge stopped working.
When I first start the Jeep it seems to read correctly, then after a minute of two, it will start to slowly drop,
then within a couple minutes it will read E, the fuel light comes on, and the check engine light , code P0462 Fuel Level Sensor 'A' Circuit Low

So, I figured it was the sending unit, and replaced the entire fuel pump assembly.
Guess what,, didnt fix it. Does the exact same thing.

Then I looked up the grounding wires for it, saw some saying that ground was behind the driver tail light.
There is one there, but seems to be only for the lights.

I then tapped into the dark blue/dark green wire (sending unit ground) coming from the fuel pump assembly,
Tested it and it had continuity with ground.
But for the hell of it, I spliced into it, and grounded it to the chassis.

Still does the same thing. Any suggestions?

 

[macleanflood]

Unwrap the wiring harness for the fuel pump assembly at least to the transfer case possibly farther and inspect the wires.

Alternatively download the FSM, factory service manuals in the resources section. 8w has the wiring diagrams. You should be able to check continuity and ohms back to the PDM relay slots and PCM connector.

I'd also use an ODB scanner to verify what the PCM sees about the fuel level. You may have a gauge cluster issue and not a sending unit issue.

-Mac

 

[JohnTrotto]

edited my post to add the code I get..
code P0462 Fuel Level Sensor 'A' Circuit Low

 

[macleanflood]

Update the details on your Jeep on your profile.

Mostly year, engine and transmission.

-Mac

 

[JohnTrotto]

Update the details on your Jeep on your profile.

Mostly year, engine and transmission.

-Mac

Done, thanks.

 

[macleanflood]

Original PCM?

-Mac

 

[JohnTrotto]

Original PCM?

-Mac

Nope, it was acting up, throttle "bouncing" in reverse, stalling, and other just, not running smooth issues.
Had to buy a Wrangler Fix ECU/PCM, which fixed all those issues.
That was in there about a year or so before the sending unit issue started.

 

[JohnTrotto]

Saw is could be the gauge cluster?
Though, I have no other issues with the cluster, no flickering, etc.
But also saw that I probably would not get the code thrown if its the cluster.
But might see how tough it is to pull it, clean the contacts and reseat the connections.

 

[macleanflood]

It's super easy and there is a self test procedure.

-Mac

 

[JohnTrotto]

It's super easy and there is a self test procedure.

-Mac

Does the self test not just test the needle motors, etc? Didnt think it checked if it was getting proper signals.
I will try that before pulling the cluster then.

 

[JohnTrotto]

Cluster self test passed.
Not sure its worth reseating the connections on it or not but might for the heck of it.
Going to also try to trace as much as that wire harness from the fuel pump as I can, see if I notice any nicks, etc.
Quickly running out of options it seems :/