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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 >> DTC P0641 >> 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.
  1. Ignition OFF. Disconnect the harness connector at the PTO switch.
  2. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 1 and ground.
    • If less than the specified range, test the 5-volt 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 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the PTO module.
  3. Clear all DTCs. Verify that P0641 sets as current in the PTO module.
    • If the specified code does not set as current, test or replace the PTO switch.
  4. Ignition OFF, connect the harness connector at the PTO switch.
  5. Disconnect the harness connector at X124.
  6. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal E at the female side of the connector and ground.
    • If less than the specified range, test the 5-volt 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 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the PTO module.
  7. Ignition ON, test for 0 volts between the 5-volt reference circuit terminal E at the male side of the connector and ground.
    • If greater than the specified value, test the 5-volt reference circuit between X124 and the upfitted remote PTO switch assembly for a short to voltage. If the circuit tests normal, test or replace the upfitted remote PTO switch assembly.
  8. Ignition OFF, test for infinite resistance between the 5-volt reference circuit terminal E at the male side of the connector and ground.
    • If less than the specified value, test the 5-volt reference circuit for a short to ground. If the circuit tests normal, test or replace the upfitted remote PTO switch assembly.
  9. If all circuits test normal, replace the PTO module.
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