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Home >> Chevrolet >> 2011 >> Volt >> Repair and Diagnosis >> External Pages >> Different car >> Section 14 (Lighting System) >> Diagnostic Information and Procedures >> DTC B257A >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2012 Chevrolet Volt. However, it is still accessible from the selected car via links, so may be relevant.
  1. Vehicle OFF, all doors closed, all accessories OFF, disconnect the harness connector at the S78 turn signal/multifunction switch. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal 6 and ground.
    • If 10 Ω or greater 
    1. Vehicle OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω 
  3. Vehicle in Service Mode.
  4. Verify the scan tool Automatic Headlamps Disable Switch parameter is Inactive.
    • If not Inactive 
    1. Vehicle OFF, disconnect the X1 harness connector at the K9 body control module.
    2. Test for infinite resistance between the signal circuit terminal 9 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K9 body control module.
    • If Inactive 
  5. Install a 3 A fused jumper wire between the signal circuit terminal 9 and the ground circuit terminal 6.
  6. Verify the scan tool Automatic Headlamps Disable Switch parameter is Active.
    • If not Active 
    1. Vehicle OFF, disconnect the X1 harness connector at the K9 body control module, vehicle in Service Mode.
    2. Test for less than 1 V between the signal circuit terminal 9 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 body control module.
    • If Active 
  7. Verify the scan tool Park Lamps Switch parameter is Inactive.
    • If not Inactive 
    1. Vehicle OFF, disconnect the X1 harness connector at the K9 body control module.
    2. Test for infinite resistance between the signal circuit terminal 7 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K9 body control module.
    • If Inactive 
  8. Install a 3 A fused jumper wire between the signal circuit terminal 7 and the ground circuit terminal 6.
  9. Verify the scan tool Park Lamps Switch parameter is Active.
    • If not Active 
    1. Vehicle OFF, disconnect the X1 harness connector at the K9 body control module, vehicle in Service Mode.
    2. Test for less than 1 V between the signal circuit terminal 7 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 body control module.
    • If Active 
  10. Verify the scan tool Headlamps On Switch parameter is Inactive.
    • If not Inactive 
    1. Vehicle OFF, disconnect the X1 harness connector at the K9 body control module.
    2. Test for infinite resistance between the signal circuit terminal 2 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K9 body control module.
    • If Inactive 
  11. Install a 3 A fused jumper wire between the signal circuit terminal 2 and the ground circuit terminal 6.
  12. Verify the scan tool Headlamps On Switch parameter is Active.
    • If not Active 
    1. Vehicle OFF, disconnect the X1 harness connector at the K9 body control module, vehicle in Service Mode.
    2. Test for less than 1 V between the signal circuit terminal 2 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 body control module.
    • If Active 
  13. Test or replace the S78 turn signal/multifunction switch.
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