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Home >> GMC >> 2021 >> Terrain SL >> Repair and Diagnosis >> External Pages >> Different car >> Section 169 (Driver Assistance Systems) >> Diagnostic Information and Procedures >> DTC B0987 >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2021 Buick Enclave. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: S26 Hazard Warning Switch
  3. Ignition/Vehicle - On
  4. Test for greater than 3 V between the test points: Control circuit terminal 8 & Ground
    • Go to next step: If greater than 3 V 
  5. Ignition/Vehicle & All vehicle systems - Off
  6. Connect the electrical connector: S26 Hazard Warning Switch
  7. Disconnect the electrical connector: B174W Frontview Camera - Windshield
  8. Ignition/Vehicle - On
  9. Verify the component is not activated: Lane Keep Assist Switch Indicator
    • If the component activates 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the electrical connector: S26 Hazard Warning Switch
    3. Test for infinite resistance between the test points: Control circuit terminal 6 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: S26 Hazard Warning Switch
    • Go to next step: If the component does not activate 
  10. Connect a 3 A fused jumper wire between the test points: Control circuit terminal 4 & Ground
  11. Verify the component activates: Lane Keep Assist Switch Indicator
    • If the component does not activate 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector: S26 Hazard Warning Switch
    3. Ignition/Vehicle - On
    4. Test for less than 1 V between the test points: Control circuit terminal 6 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    5. Test for less than 2 Ω between the test points: Control circuit terminal 6 @ Component harness & Control circuit terminal 4 @ Control module harness
      • If 2 Ω or greater - Repair the open/high resistance in the circuit.
      • If less than 2 Ω - Replace the component: S26 Hazard Warning Switch
    • Go to next step: If the component activates 
  12. Test or replace the component: B174W Frontview Camera - Windshield
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