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Home >> Chevrolet >> 2017 >> Traverse Premier, AWD >> Repair and Diagnosis >> Electrical >> Charging Systems >> Battery, Charging System And Starting System >> Diagnostic Information and Procedures >> DTC P0621: Generator L-Terminal Circuit >> Circuit/System Testing
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Circuit/System Testing

  1. Verify a test lamp illuminates between the G13 Generator B+ circuit terminal A X1, A X2, B X2, 1 X1 or 1 X2 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Remove the test lamp and disconnect the B+ cable at the G13 Generator
    2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Remove the test lamp, disconnect the battery negative cable, and disconnect the G13 Generator B+ cable.
    2. Test for infinite resistance between the B+ circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace G13 Generator.
    • If the test lamp illuminates 
  2. Disconnect the X1 harness connector at the G13 Generator, engine running.
  3. Test for 1 V or greater between the control circuit terminal 1 X1 and ground.
    • If less than 1 V 
    1. Ignition OFF, disconnect the harness connectors at the K20 Engine Control Module.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the control circuit end to end.
      • If greater than 2 Ω, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K20 Engine Control Module.
    • If 1V or greater 
  4. Ignition OFF, disconnect the harness connectors at the K20 Engine Control Module, Ignition ON
  5. Test for less than 1 V between the G13 Generator control circuit terminal 1 X1 and ground.
    • If greater than 1 V 

      Repair the short to voltage on the circuit.

    • If 1V or less 
  6. Test or replace the G13 Generator.
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