The power take-off (PTO) is an upfitter integrated system that allows the user to create an auxiliary power source. The PTO system specifically controls engine speed to values higher than normal base idle, PTO load relay engagement, and remote starting and shutdown of the engine. When the operator requests PTO using either the PTO switch or PTO remote, the engine RPM will increase to a default standby speed. The engine control module (ECM) converts the data from the engine speed sensor to a 2 pulses/engine revolution signal. When PTO is engaged, the power take-off module (PTOM) sends a GMLAN serial data message to the ECM requesting engine speeds, in accordance with the depressed switches from the PTO switch or remote.

Schematic Reference

Power Take-Off (PTO) Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Power Take-Off (PTO) Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Engine ON, observe the PTO In Cab Switch parameter with a scan tool. Press 1 on the PTO switch to engage PTO. The engine RPM should increase to the default engine speed within a few seconds. Press 0 to disengage PTO and to return the engine speed back to normal idle. The PTO In Cab Switch parameter should change accordingly with the depressed switch.
2. Engine OFF, key out of ignition, observe the PTO Remote Switch Status with a scan tool. Enable PTO using the upfitted remote switch assembly (if equipped). The engine RPM should increase to the default engine speed within a few seconds. Use the upfitted remote switch assembly to disengage PTO and the engine should shut down. The PTO Remote Switch Status parameter should change accordingly with the depressed remote switch.

PTO In Cab Switch

1. Engine ON, engage PTO. Observe the PTO In Cab Switch parameter with a scan tool. Verify that the PTO In Cab Switch parameter matches each depressed switch: RES +, SET -.

⇒	If any one of the switches do not match accordingly with the scan too parameter, replace the PTO switch.

2. If all circuits test normal, replace the PTO module.

Upfitted Remote Switch Assembly

1. Engage PTO using the upfitted remote switch assembly. Observe the PTO Remote Switch Status parameter with a scan tool. Verify that the PTO Remote Switch Status parameter matches each depressed switch for increasing and decreasing engine RPM.

⇒	If any one of the switches do not match accordingly with the scan tool parameter, replace the upfitted remote switch assembly.

2. If all circuits test normal, replace the PTO module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.