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Home >> Buick >> 2012 >> Regal Turbo, Automatic Trans >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Interior/Illumination Lights >> Lighting System >> Diagnostic Information and Procedures >> DTC B3948 or B3949 >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the appropriate E4 turn signal lamp.
  2. Test for less than 30 Ω between the ground circuit terminal listed below and ground:
    • Turn signal lamp - front - terminal 1
    • Turn signal repeater lamp - terminal 2
    • If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal listed below and ground:
    • Turn signal lamp - front - terminal 5
    • Turn signal repeater lamp - terminal 1
  4. Command the appropriate Front Turn Signal Lamp 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 signal circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
    • If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the K9 BCM.
  5. If all circuits test normal, replace the E4 turn signal lamp.
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