Vehicle: 2005 GMC Truck Sierra 1500 4WD V8-5.3L VIN T Automatic Transmission/Transaxle
Problem: Truck was running fine and then one morning it would not start and the instrument cluster displayed a “Reduced Power” message. The MIL was ON.
Details: The Technician retrieved DTCs U1000, U0107, U1016, P1516, P2120 and P2125 and then checked the throttle control system PIDs. The Throttle Position Sensors 1 and 2 were not responding. The throttle plate was free and not binding. The tech tested throttle control circuits at the Throttle Actuator Control Module. He found only 3.9 volts on the 5-volt reference output at pin #9, good battery voltage at the power input at pin #7 and no ground at pin #15.
Confirmed Repair: The tech found that the wire to ground (#G104), located at the right rear of the engine block directly below the intake manifold, was chewed completely through by rodents. He repaired the wire harness and ground; the engine started and ran with no DTCs.