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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1555 (Battery, Charging System And Starting System - Non-Hybrid) >> Diagnostic Information and Procedures >> DTC P0622 (Diesel) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the X1 harness connector at the generator.
  2. Ignition ON, verify the scan tool ECM GEN-F Terminal Signal parameter is 0%.
    • If greater than the specified value, test the field duty cycle circuit terminal 2 for a short to voltage. If the circuit tests normal, replace the ECM.
  3. Connect a test lamp between the field duty cycle circuit terminal 2 and B+. Verify the scan tool ECM GEN-F Terminal Signal parameter is greater than 95%.
    • If less than the specified range, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
  4. If all circuits test normal, test or replace the generator.