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Home >> Chevrolet >> 2015 >> Cruze LT, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 40 (Hydraulic Brake System) >> Diagnostic Information and Procedures >> Brake Booster Pump Motor Malfunction (With J41) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2015 Chevrolet Trax and 2015 Buick Encore. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF and all vehicle systems OFF, disconnect the KR14 Brake Booster Pump Motor Relay. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal 1 (86) and ground.
    • If 10 Ω or greater 
    1. Ignition 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. Ignition ON.
  4. Verify a test lamp illuminates between the B+ circuit terminal 3 (30) and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF.
    2. Test for infinite resistance between the B+ circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Disconnect the M9 Brake Booster Pump Motor.
    4. Test for infinite resistance between the control circuit terminal 5 (87) and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the KR14 Brake Booster Pump Motor Relay.
    • If the test lamp illuminates 
  5. Ignition OFF, disconnect the B19C Brake Booster Vacuum Switch, ignition ON.
  6. Verify a test lamp illuminates between ignition circuit terminal 1 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF.
    2. Test for infinite resistance between the ignition circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for infinite resistance between the B19C Brake Booster Vacuum Switch terminal 2 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the KR14 Brake Booster Pump Motor Relay.
    • If the test lamp illuminates 
  7. Connect a test lamp between the KR14 Brake Booster Pump Motor Relay control circuit terminal 2 (85) and the ground circuit terminal 1 (86).
    • If the test lamp illuminates  

      Repair the short to voltage on the control circuit

    • If the test lamp does not illuminate 
  8. Ignition OFF, connect the B19C Brake Booster Vacuum Switch. Remove the vacuum hose from the brake booster to deplete the vacuum in the system, ignition ON. Verify the test lamp illuminates
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the harness connector at the B19C Brake Booster Vacuum Switch.
    2. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the B19C Brake Booster Vacuum Switch.
    • If the test lamp illuminates 
  9. Verify that a test lamp does not illuminate between the relay control circuit terminal 5 (87) and ground.
    • If the test lamp illuminates  

      Repair the short to voltage on the control circuit

    • If the test lamp does not illuminate 
  10. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the M9 Brake Booster Pump Motor. It may take up to 2 min for all vehicle systems to power down.
  11. Test for less than 10 Ω between the M9 Brake Booster Pump Motor ground circuit terminal 2 and ground.
    • If 10 Ω or greater 
    1. 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 
  12. Connect the harness connector at the M9 Brake Booster Pump Motor.
  13. Ignition ON, connect a 30 A fused jumper wire between the B+ circuit terminal 3 (30) and the control circuit terminal 5 (87).
  14. Verify the M9 Brake Booster Pump Motor is activated.
    • If the M9 Brake Booster Pump Motor does not activate 
    1. Ignition OFF, disconnect the harness connector at the M9 Brake Booster Pump Motor.
    2. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the M9 Brake Booster Pump Motor.
    • If the M9 Brake Booster Pump Motor activates 
  15. Test or replace the KR14 Brake Booster Pump Motor Relay.
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