LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Cadillac >> 2009 >> Escalade EXT >> Repair and Diagnosis >> Electrical >> Charging Systems >> Battery, Charging System And Starting System >> Diagnostic Information and Procedures >> DTC P0621 >> Circuit/System Testing
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Circuit/System Testing

  1. Ignition OFF, disconnect the X1 harness connector at the generator.
  2. Ignition ON, test for less than 1 V between the signal circuit terminal 1 and ground.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  3. Engine running, test for greater than 3.5 V between the signal circuit terminal 1 and ground.
    • If less than the specified range, test the signal 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.
scientia non olet · About LEMON Manuals