Fuel sending unit resistance

[GSX455]

I installed my sending unit and fixed the broken quick disconnects with Larry B's kit.  

My fuel gauge still does not work.  I did the cluster check, hold the odometer button down, and the gauge functions, etc.

The resistance when the tank is empty was about 210-215 ohms; 20 ohms when the level is moved to full.

I get these readings at the connector on top of the tank. Is there anything else, besides the harness being bad, that would make the fuel gauge not read? 

 

Thanks for any suggestions, the truck has 350k miles, and things are breaking down at an alarming rate. 

 

 

 

 

 

 

[Mopar1973Man]

Did you get the sender in the right 2 pin positions? Did you get it fully plugged in the bottom and locked again? Did you test at the socket at the front fender for ohm signal? Is that socket corroded or damaged?

Edited September 12, 2016 by Mopar1973Man

[IBMobile]

Also there should be battery voltage at the black/light blue wire at the sender. this voltage comes from pin # 17 at the PDC.  The voltage should be less on the dark blue/white wire that comes out of the fuel sender and goes to pin # 26 in the C3 connector at the PCM.  The change in resistance of the fuel gauge changes the voltage to the PCM.  The PCM then sends the value over the CCD to the instrument cluster circuit board where an algorithm is applied to find the correct needle position.  If you do not have voltage at the sender or at C3 pin #26 it may be a bad connection or a bad wire.

[GSX455]

The original had the pins from the unit in the middle 2, so I did the same as the original.  I'll try the right 2 pins..  Socket to the wiring harness looked okay, the Molex type pins had locked into the inner harness   

The more forum posts I look at the more convinced I am to ditch the OEM in tank pump and go to a draw straw and remote draw location.   Fuel pressure is at 15 psi on the gauge.   

 

Thank you for your help!  

[GSX455]

 

On 9/11/2016 at 8:36 PM, IBMobile said:

Also there should be battery voltage at the black/light blue wire at the sender. this voltage comes from pin # 17 at the PDC.  The voltage should be less on the dark blue/white wire that comes out of the fuel sender and goes to pin # 26 in the C3 connector at the PCM.  The change in resistance of the fuel gauge changes the voltage to the PCM.  The PCM then sends the value over the CCD to the instrument cluster circuit board where an algorithm is applied to find the correct needle position.  If you do not have voltage at the sender or at C3 pin #26 it may be a bad connection or a bad wire.

   

So there is no voltage at the PCM, even jumping to 2 leads from the harness did not make the gauge move. The harness was connected tight to the sending unit. The truck was taken to a garage, and they traced it to the PCM, So, I need a new PCM?  Is there a way to program the PCM and the VIN.  

 

Any other suggestions?    

 

Thanks for any help, again.

[IBMobile]

 

Voltage comes from PCM plug #3 pin #26 to the sender then to pin #17 of the joint connector at the PDC then goes to ground.

 

Edited September 25, 2016 by IBMobile
mistake, clarify

[GSX455]

No, there was no voltage at the BLK_LTBLU at the PDC wire connector with the ignition on.  There was 0.22 volts without the ignition on.    .

 

[Hawkez]

Is that wire damaged?  I look smashed at the top.

[IBMobile]

4 hours ago, GSX455 said:

No, there was no voltage at the BLK_LTBLU at the PDC wire connector with the ignition on.  There was 0.22 volts without the ignition on.    .

  Since the BK/LT BLU wire was at joint connector #1 in the power distribution center I assumed it was battery voltage.  After reading this I took another look at the wire diagrams.  Pins 15-18 go to ground and that's why there is no voltage.  Sorry, that's what happens when I assume.

   The voltage does come from the PCM Plug #3 pin #26 dark blue/white wire.  I was doing an oil change on the truck today so while I was under there I took some readings at the connector by the left front wheel well. 

   With a 1/4 tank of fuel the sender read 164 ohms between the DK BL/WT and BK/LT BL wires. 

 

The BK/LT BL wire that goes to ground showed 6 ohms between the female connector and ground at the battery.

The DK BL/WT wire from the PCM showed 11.3 volts with key on.

 

[GSX455]

That was very helpful, thank you for taking the time to check this out. 

So between the two leads from the tank, I got MOhms between the 2 male connectors, DK BL/WH and BK/LT BL, tried leads twice.

 

I have 11.39 volts from the PCM, and 24 ohms from the battery ground to the female connector on the PCM.

 

So my harness to the tank is bad, apparently, because I got 220 ohms on an empty tank at the sender leads.  Would Larry B's carry this harness? 

 

[IBMobile]

4 hours ago, GSX455 said:

That was very helpful, thank you for taking the time to check this out. 

So between the two leads from the tank, I got MOhms between the 2 male connectors, DK BL/WH and BK/LT BL, tried leads twice.

 

I have 11.39 volts from the PCM, and 24 ohms from the battery ground to the female connector on the PCM.

 

So my harness to the tank is bad, apparently, because I got 220 ohms on an empty tank at the sender leads.  Would Larry B's carry this harness? 

 

   So 220 ohms at sender and infinity reading at the male connector by the left front wheel well.  I'd say you have an open circuit and need to repair/replace a wire or two.

   I don't know if Larry B's carries it or not but for the price of 4 heat shrink solder sleeve butt connector and a roll of 18-16 gauge wire you could have it fixed.