LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Buick >> 2013 >> Verano Base >> Repair and Diagnosis >> External Pages >> Different car >> Section 88 (Battery, Charging System And Starting System) >> Diagnostic Information and Procedures >> DTC P0621 >> Circuit/System Testing >> LAP Engine
April 5, 2026: LEMON Manuals is launched! Read the announcement.

LAP Engine

WARNING: This page is about a different car, the 2010 Pontiac G5 and 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
  1. Verify that a test lamp illuminates between the generator B+ terminal X2 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  2. Ignition OFF, disconnect the X1 harness connector at the generator.
  3. Ignition ON, test for 4.5-5.5 V between the control circuit terminal 1 and ground.
    • If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
    • If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal replace the ECM.
  4. If the circuits test normal, replace the generator.
scientia non olet · About LEMON Manuals