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Home >> Chevrolet >> 2004 >> Impala LS >> Repair and Diagnosis >> External Pages >> Different car >> Section 742 (Mirror Systems) >> Diagnostic Information and Procedures >> Heated Mirrors Inoperative >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2008 Buick Lucerne. 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 outside rearview mirror.
  2. Test for less than 10 ohms between the ground circuit terminal 3 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the door module.
  3. Connect a test lamp between the control circuit terminal 4 and ground.
  4. Ignition ON, command the mirror heater ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the door module.
    • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the door module.
  5. If all circuits test normal, test or replace the outside rearview mirror glass.
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