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HOMESERVICE MANUALSBUICK2018REGAL BASEREPAIR AND DIAGNOSISACCESSORIES & EQUIPMENTSTEERING COLUMN SWITCHESSECONDARY AND CONFIGURABLE CUSTOMER CONTROL SYSTEMDIAGNOSTIC INFORMATION AND PROCEDURESDTC B074BCIRCUIT/SYSTEM TESTING
2018 Buick Regal Base

Circuit/System Testing

2018 Buick Regal BaseSECTION Circuit/System Testing
  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: S48E Multifunction Switch - Center Console
  3. Ignition - On / Vehicle - In Service Mode
  4. Headlamp Switch=On
  5. Verify a test lamp turns On between the test points: Control circuit terminal 3 & Ground
    • Go to next step: If the test lamp turns On 
  6. Ignition/Vehicle - Off & Remove - Test lamp
  7. Connect the electrical connector: S48E Multifunction Switch - Center Console
  8. Disconnect the electrical connector: X5@K9 Body Control Module
  9. Ignition - On / Vehicle - In Service Mode
  10. Headlamp Switch=On
  11. Verify the component works as specified: Sport Mode - LED (Light Emitting Diode)@S48E Multifunction Switch - Center Console=Off
    • If the component does not work as specified 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: S48E Multifunction Switch - Center Console
    3. Test for infinite resistance between the test points: Control circuit terminal 8 X5@Control module harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: S48E Multifunction Switch - Center Console
    • Go to next step: If the component works as specified 
  12. Connect a 3 A fused jumper wire between the test points: Control circuit terminal 8 X5 & Ground

    Verify the component works as specified: Tour Mode - LED (Light Emitting Diode)@S48E Multifunction Switch - Center Console=On

    • If the component does not work as specified 
    1. Disconnect the electrical connector: S48E Multifunction Switch - Center Console
    2. Test for less than 1 V between the test points: Control circuit terminal 8 X5@Control module harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    3. Ignition/Vehicle - Off
    4. Test for less than 2 ohms between the test points: Control circuit terminal 8 X5@Control module harness & Control circuit terminal 13@Component harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: S48E Multifunction Switch - Center Console
    • Go to next step: If the component works as specified 
  13. Replace the component: K9 Body Control Module
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.