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HOMESERVICE MANUALSCHEVROLET2025TRAILBLAZER ACTIV, FWDREPAIR AND DIAGNOSISTRANSMISSIONAUTOMATIC TRANSSHIFT LOCK CONTROL SYSTEMDIAGNOSTIC INFORMATION AND PROCEDURESTRANSMISSION CONTROL LEVER MALFUNCTIONCIRCUIT/SYSTEM TESTING
2025 Chevrolet Trailblazer ACTIV, FWD

Circuit/System Testing

2025 Chevrolet Trailblazer ACTIV, FWDSECTION Circuit/System Testing
  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: X5K9 Body Control Module
  3. Ignition - On / Vehicle - In Service Mode
  4. Verify a test lamp turns On between the test points: B+ circuit terminal 4 & Ground
    • If the test lamp does not turn On and the circuit fuse is OK 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Test for less than 2 ohms between the test points: B+ circuit terminal 4 & Output terminal @ Fuse
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.
    • If the test lamp does not turn On and the circuit fuse is open 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector: X7K9 Body Control Module
    3. Test for infinite resistance between the test points: Control circuit terminal 6 & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: K9 Body Control Module
    • Go to next step: If the test lamp turns On 
    5. NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  5. Ignition/Vehicle & All vehicle systems - Off
  6. Disconnect the electrical connector: S3 Transmission Shift Lever
  7. Test for less than 10 ohms between the test points: Ground circuit terminal 4 & Ground
    • If 10 ohms or greater 
    1. Disconnect ground terminal.
    2. Test for less than 2 ohms between the test points: Ground circuit terminal 4 & Ground
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Repair the open/high resistance in the ground connection.
    • Go to next step: If less than 10 ohms 
  8. Connect a test lamp between the test points: Control circuit terminal 1 & Ground circuit terminal 4
  9. Ignition - On / Vehicle - In Service Mode
  10. Perform the scan tool control function: Brake Transmission Shift Interlock Solenoid Actuator

    Verify the test lamp turns On and Off.

    • If the test lamp is always Off 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector: K9 Body Control Module
    3. Test for infinite resistance between the test points: Control circuit terminal 1 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    4. Test for less than 2 ohms between the test points: Control circuit terminal 1 @ Component harness & Terminal 6 X7 @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K9 Body Control Module
    • If the test lamp is always On 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector: K9 Body Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Control circuit terminal 1 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Replace the component: K9 Body Control Module
      • Go to next step: If the test lamp turns On and Off 
    5. Test or replace the component: S3 Transmission Shift Lever
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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.