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Home >> Cadillac >> 2012 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 1345 (Power Take-Off System) >> Diagnostic Information and Procedures >> Power Take-Off (PTO) Does Not Engage >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, and 2009 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

PTO In Cab Switch

  1. Ignition OFF, disconnect the harness connector at the PTO module.
  2. Ignition ON, test for 11 volts or greater between the B+ circuit terminal 32 and ground.
    • If less than the specified voltage, test the B+ circuit for a short to ground or an open/high resistance.
  3. Ignition OFF, connect the harness connector at the PTO module.
  4. Ignition OFF, disconnect the harness connector at the PTO switch.
  5. Ignition ON, test for 4.8-5.2 volts between the 5V reference circuit terminal 1 and ground.
    • If less than the specified range, test the 5V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the PTO module.
    • If greater than the specified range, test the 5V reference circuit for a short to voltage. If a short to voltage is found and repaired, replace the PTO switch. If the circuit tests normal, replace the PTO module and the PTO switch.
  6. Connect the harness connector at the PTO switch.
  7. Engine ON, observe the PTO In Cab Switch parameter with a scan tool. Verify that the PTO In Cab Switch parameter matches each depressed switch: 1, 0, RES +, SET -.
    • If any one of the switches do not match accordingly with the scan tool parameter, replace the PTO switch.
  8. If all circuits test normal, replace the PTO module.

Upfitted Remote Switch Assembly

  1. Ignition OFF, disconnect the harness connector at the PTO module.
  2. Ignition ON, test for 11 volts or greater between the B+ circuit terminal 32 and ground.
    • If less than the specified voltage, test the B+ circuit for a short to ground or an open/high resistance.
  3. Ignition OFF, connect the harness connector at the PTO module.
  4. Ignition OFF, disconnect the harness connector X124.
  5. Ignition ON, test for 4.8-5.2 volts between the 5V reference circuit terminal E and ground.
    • If less than the specified range, test the 5V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the PTO module.
    • If greater than the specified range, test the 5V reference circuit for a short to voltage. If the circuit tests normal, replace the PTO module.
  6. Connect the harness connector X124.
  7. 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.
    • If any one of the switches do not match accordingly with the scan tool parameter or if PTO does not engage, replace the upfitted remote switch assembly.
  8. If all circuits test normal, replace the PTO module.
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