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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 81 (Mirrors) >> Diagnostic Information and Procedures >> Power Mirror Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the power mirror switch.
  2. Test for less than 10 Ω between the ground circuit terminal D and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal E and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuits for a short to ground.
  4. Connect the harness connector at the outside rearview mirror switch.
  5. Disconnect the harness connector at the appropriate power mirror.
  6. Connect a test lamp between the control circuit terminal F and the control circuit terminal E.
  7. Operate the vertical switch UP and DOWN. The test lamp should turn ON when commanding the UP and DOWN states.
    • If the test lamp remains OFF during either of the commands, test for a short to voltage, short to ground or an open/high resistance on the control circuits. If the circuits test normal, replace the power mirror switch.
  8. Connect a test lamp between the control circuit terminal G and the control circuit terminal H.
  9. Operate the horizontal switch LEFT and RIGHT. The test lamp should turn ON when commanding the LEFT and RIGHT states.
    • If the test lamp remains OFF during either of the commands, test for a short to voltage, short to ground or an open/high resistance on the control circuits. If the circuits test normal, replace the power mirror switch.
  10. If all circuits test normal, test or replace the power mirror.
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