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So ever since I bought the truck, my gas gauge never worked. After a year of it I am SICK of it and would love to have the gauge back. The truck throws a low or high voltage code (I can't remember the exact code/description....it has been a while since I scanned her) because of this. Anyone have any idea at all of what it could be? I already tried replacing the sender unit. When I clear the codes, it reads full for a second or two, then drops back to empty. Input or first steps to take? Thanks!
 

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Bad float or sensor? :shrug:
 

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Bad float or sensor? :shrug:
When I took the bed off to replace the sending unit, everything looked okay. Replaced the float and it acted just like when I cleared the codes. I was thinking maybe something in the wiring could be bad too..
 

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Since you have replaced the sending unit, you will know if that connector is good or not. The control of the fuel gauge is by the PCM over the Serial Data Bus. If the other indicators are working normally (they work off the Data Bus also) we can assume that the connect from the PCM to the instrument cluster is probably good.

That gets us to the wiring from the sending unit to the PCM. On its way to the PCM, the circuit goes through inline connector C102. This is a 16 pin connector located in the engine compartment, left center wheel well, aft of the battery, next to the EBCM (Electronic Brake Control Module). There could be a bit of fretting corrosion on the pins. Disconnect it and check inside. The signal from the fuel quantity sender is the purple wire. The ground for the circuit is the black wire next to the purple one. Connect/reconnect the halves several times to establish good pin contact. Check the gauge to see if you got lucky.

If that didn't help, the only other thing that I see right now is the connector to the PCM. Do the same procedure to it. The connector in question is C1. It should be blue. The wire colors are the same, except there are several purple wires and more than one black. Good luck.

Just remembered one last possibility, but it isn't good. It could be the stepper motor, in the instrument cluster, that drives the needle. They can be changed, but they require a steady hand with a soldering iron.
 

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Bumping an old thread. Ryley did that work?

And Cart. Any chance the wiring for the 4wd goes through this same place? Im having both 4wd not engaging and this same fuel gauge issue. After throwing a lot of parts at the 4wd I am thinking the problems may be connected

Since you have replaced the sending unit, you will know if that connector is good or not. The control of the fuel gauge is by the PCM over the Serial Data Bus. If the other indicators are working normally (they work off the Data Bus also) we can assume that the connect from the PCM to the instrument cluster is probably good.

That gets us to the wiring from the sending unit to the PCM. On its way to the PCM, the circuit goes through inline connector C102. This is a 16 pin connector located in the engine compartment, left center wheel well, aft of the battery, next to the EBCM (Electronic Brake Control Module). There could be a bit of fretting corrosion on the pins. Disconnect it and check inside. The signal from the fuel quantity sender is the purple wire. The ground for the circuit is the black wire next to the purple one. Connect/reconnect the halves several times to establish good pin contact. Check the gauge to see if you got lucky.

If that didn't help, the only other thing that I see right now is the connector to the PCM. Do the same procedure to it. The connector in question is C1. It should be blue. The wire colors are the same, except there are several purple wires and more than one black. Good luck.

Just remembered one last possibility, but it isn't good. It could be the stepper motor, in the instrument cluster, that drives the needle. They can be changed, but they require a steady hand with a soldering iron.
 

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It doesn't appear that any of the circuits for the 4wd go through that connector. I haven't found a connection between the two systems, yet.
 
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