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Home >> Pontiac >> 2009 >> Torrent Base, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 157 (Lighting Systems) >> Diagnostic Information and Procedures >> DTC B257A >> Circuit/System Testing

Circuit/System Testing

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2009 GMC Savana Special, 2009 GMC Savana Camper Special, 2009 GMC Savana, 2009 Chevrolet RV Cutaway, and 2009 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the headlamp switch.
  2. Ignition ON, test for B+ between the signal circuit terminals listed below and ground.
    • Headlamp switch ON signal terminal 1
    • Park lamp switch ON signal terminal 2
    • Headlamp switch OFF signal terminal 3
    • If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  3. Install a 3A fused jumper wire between the park lamp ON signal circuit terminal 2 and ground. Verify the scan tool Parklamp Switch parameter is Active.
    • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  4. If all circuits test normal, replace the headlamp switch.
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