Silverado Classic 1500 4WD V8-5.3L Hybrid (2007)
Power Take-Off: Testing and Inspection
Engine RPM Does Not Increase With Power Take-Off Engaged
Engine RPM Does Not Increase with Power Take-Off Engaged
Circuit Description
When the power take-off (PTO) switch is turned to the ON position and all PTO engage conditions are met, the engine RPM should increase to the
standby speed. When the powertrain control module (PCM) receives the signal from the PTO switch the PCM will send a signal to the throttle actuator
control module (TAC). The TAC module controls the TAC motor which changes the position of the throttle. Communications between the two modules
is monitored and checked for accuracy by the PCM. DTCs may be recorded in the event of the failure. The 6.6L diesel engine does not have a TAC
system and the engine RPM is strictly controlled by the engine control module (ECM) and the Fuel Injection Control Module.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. This step checks for other system DTCs that may affect the PTO.
6. This step tests the PCM for the PTO Enable signal.
7. This step tests the communication between the PCM and the TAC module.
8. This step tests the PTO On Switch Signal circuit.
9. This step tests the PTO On Switch-Signal circuit for an open, high resistance or short to ground.
10. This step tests the Serial Data circuits for an open, high resistance or short to ground.
