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.