How to measure fuel level signal?

[Crunchy Monkey]

The fuel gauge on my 2003 Yukon XL randomly shifts between the correct reading, showing empty, or somewhere in between. Luckily I can use the "personal gallons consumed" reading to accurately determine the tank status. Now I need to determine if the issue is with the sending unit on/in the tank or with the instrument cluster display. Does anyone know if the display is driven by an analog signal? If so, on which wire?

 

[rockola1971]

Check your ground wire (loose, broken, corrosion) up on top of the tank. Have fun with that while you are doing it too.

 

[rockola1971]

The signal is analog. 0-5vdc using chassis ground as a ground reference. The PCM provides signal power. Empty should read around .71v and full around 2.53. Half tank would be around 1.62v. This is assuming your fuel level sensor is a 240 ohm unit. This is measured at a connector on your wiring harness to the PCM.

 

[Crunchy Monkey]

The signal is analog. 0-5vdc using chassis ground as a ground reference. The PCM provides signal power. Empty should read around .71v and full around 2.53. Half tank would be around 1.62v. This is assuming your fuel level sensor is a 240 ohm unit. This is measured at a connector on your wiring harness to the PCM.

Great info, thanks! Do you happen to know which pin/wire it is on the instrument cluster connector?