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

Power Take-Off (PTO) Connector End Views

Description and Operation

Power Take-Off (PTO) Description and Operation

Electrical Information Reference

Scan Tool Reference

1. Verify that the interior backlighting system operate normally. Refer to Interior Lighting Systems Description and Operation .
2. Ignition ON, install a scan tool and verify that DTC P260D is not set as current.

⇒	If the specified DTC is set as current, refer to DTC P260D .

3. Ignition ON, with the scan tool, command the PTO Indicator ON and OFF. The PTO indicator in the PTO switch should illuminate ON and OFF accordingly.

⇒	If the indicator is illuminates ON and OFF accordingly, replace the PTO module.

Important: If the interior backlighting is malfunctioning, refer to Interior Backlighting Does Not Dim or Interior Backlighting Inoperative before performing this diagnostic.

1. Ignition OFF, disconnect the harness connector at the PTO switch.
2. Connect a test lamp between LED dimming supply circuit terminal 7 and ground.
3. Ignition OFF, turn the headlamps ON and OFF. The test lamp should turn ON and OFF accordingly with the headlamp switch.

⇒	If the test lamp is always ON, test the LED dimming supply circuit for a short to voltage.

⇒	If the test lamp is always OFF, test the LED dimming supply circuit for a short to ground or an open/high resistance.

4. Ignition ON, verify that a test lamp does not illuminate between the PTO switch indicator control circuit terminal 8 and ground.

⇒	If the test lamp illuminates, test the PTO switch indicator control circuit for a short to voltage. If the circuit tests normal, test or replace the PTO module.

5. Ignition OFF, PTO OFF, verify that a test lamp does not illuminate between the PTO switch indicator control circuit and B+.

⇒	If the test lamp illuminates, test the PTO switch indicator control circuit for a short to ground. If the circuit tests normal, test or replace the PTO module.

6. Ignition OFF, disconnect the harness connector at the PTO module.
7. Ignition OFF, test for less than 1.0 ohm of resistance on the PTO switch indicator control circuit between the PTO switch terminal 8 and the PTO module terminal 9.

⇒	If greater than the specified range, test the PTO switch indicator control circuit for an open/high resistance.

8. If all circuits test normal, test or replace the PTO switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.