GMC Troubleshooting Questions? Ask a Mechanic for Answers
Hi, I' m Chad. Welcome to JustAnswer. I' m reviewing your question now, and I will be post back with your reply ASAP
how many miles on the truck ?
Did you ran a diagnostic scan and was there any fault codes ?
Fuel Level Sensor The fuel level sensor consists of a float, a wire float arm, and a ceramic resistor cord. The position of the float arm indicates the fuel level. The fuel level sensor contains a variable resistor, which changes resistance in correspondence to the amount of fuel in the fuel tank. The engine control module (ECM) sends the fuel level information via the class 2 circuit to the instrument panel (I/P) cluster. This information is used for the I/P fuel gauge and the low fuel warning indicator, if applicable. The ECM also monitors the fuel level input for various diagnostics.
The flow of circuit is from fuel level sensor to ECM ( engine computer ) to i/p ( instrument cluster )
if sending unit is good and we getting the correct power & grounds to ECM you might a defective I/P Fuel gauge ? the back connector on the I/P needs checking for a metled or burned pin to the gauge, you have to pull it out and physically look at it
let me look up the circuit diagram on it and I will get back to you .
Thank YouChad FarhatASE Certified Technician
PIN # ***** on the ecm connector # ***** ( there should be 3 connectors on the ECM ) should be fuel level sensor primary with a wire color PU (purple)
PIN # ***** on the ECM connector # ***** should be FUEL LEVEL SENSOR SECONDARY SIGNAL wire color L-BU ( light blue )
what are you getting on those ?
please let me know