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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1808 (Power Door Lock System And Release Systems) >> Diagnostic Information and Procedures >> DTC B3127, B3128, B3132, B3133, B3137, or B3138 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the appropriate relay.
  2. Test for less than 1 ohm of resistance between the relay coil ground circuit and ground.
    • If greater than the specified range, test the relay ground circuit for an open/high resistance.
  3. Connect a test lamp between the relay coil control circuit and the relay coil ground circuit.
  4. Command the appropriate relay 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 OFF, test the relay coil control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
    • If the test lamp is always ON, test the relay coil control circuit for a short to voltage. If the circuit tests normal, replace the BCM
  5. If all circuits test normal, test or replace the appropriate relay.
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