Power Take-Off (PTO) Does Not Engage

Power Take-Off (PTO) Does Not Engage

Circuit Description

This symptom chart will aid in diagnosing a failed Power Take-Off (PTO) solenoid engagement. This diagnostic will not expose a mechanical problem with the PTO itself or any fault with a specific upfitter part. This symptom chart will diagnose original equipment parts only. Refer to upfitter instructions for upfitter supplied parts. Voltage is supplied with the ignition switch in RUN and START through the ignition switch circuit breaker to the PTO Switch. When the PTO Switch is turned to ON, voltage will be present at the PTO Switch Output Enable circuit at both the PCM and the PTO upfitter connector. When the PCM sees all the necessary conditions to turn the PTO Solenoid ON it will provide a ground for the PTO Relay on the PTO Control circuit. When the PTO Relay is energized the contacts will close and current will flow to the PTO Solenoid. The PTO Solenoid has its own ground wire.

Test Description

The numbers below refer to the step numbers on the diagnostic table.
2. This step tests Engine Controls and Cruise Control for DTCs.
3. This step tests for shorts to ground.
4. This step tests for voltage on the Ignition 1 Voltage circuit.
5. This step tests for voltage on the PTO Switch Output Enable circuit.
6. This step tests for voltage on the PTO Switch Output Enable circuit at the PCM and Upfitter connector.
7. This step tests for continuity on the PTO Engage Signal circuit.
8. This step tests the PCMs ability to ground the PTO Control circuit.
9. This step tests for the location of the short to ground.