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Home >> Cadillac >> 2021 >> CT4 Sport, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 135 (12 V Starting And Charging - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> Starter Malfunction (LF4) >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition ON.
  2. Verify that no ignition, starter relay, brake pedal position sensor, immobilizer, engine, or transmission related DTCs are set that could cause the ECM to disable engine starting.
    • Go to next step: If no DTCs are set 
    3. NOTE:

    Steps 2 and 3 are for vehicles equipped with a push button ignition switch. If the vehicle is not equipped with a push button ignition switch, continue to step 4.

  3. Verify the scan tool parameter for the brake pedal position sensor is active with the brake pedal pressed.
    • If not the specified value 

      Refer to Stop Lamps Malfunction for diagnosis of the B22 Brake Pedal Position Sensor.

    • Go to next step: If the specified value 
  4. Verify the scan tool parameter for the brake pedal position sensor is inactive with the brake pedal released.
    • If not the specified value 

      Refer to Stop Lamps Malfunction for diagnosis of the B22 Brake Pedal Position Sensor.

    • Go to next step: If the specified value 
  5. Verify there are no B315A Transmission Range Control Valve 1 Position Switch system related DTCs.
    • Go to next step: If a related DTC is not set 
  6. Verify the scan tool parameters for the B315A Transmission Range Control Valve 1 Position Switch are the correct values.

    Refer to K71 Transmission Control Module: Scan Tool Information (10L60 (MQA) or 10L80 (MHU)) , or K71 Transmission Control Module: Scan Tool Information (8L45 (M5N))

    • Go to next step: If the specified values 
  7. Ignition Crank, verify the BCM scan tool Power Mode parameter is Crank Request.
    • Go to next step: If the specified state 
  8. Verify the scan tool Crankshaft Position Sensor RPM parameter does not increment.
    • If the parameter value increments 

      Replace the B26 Crankshaft Position Sensor.

    • Go to next step: If the parameter value does not increment 
  9. Verify the Engine will rotate.
    • If the engine will not rotate 
    1. Verify all of the components on the drive belt system are not seized.
    2. Verify the engine is not seized.
      • If a Component is seized

        Repair the condition.

    • Go to next step: If a condition is not found 
  10. Ignition Crank, Verify the starter engages and the engine cranks.
    • if the M64 Starter Motor spins and the engine is not cranking 

      Refer to Circuit/System Testing: Starter Test.

    • Go to next step: If the M64 Starter Motor spins and the engine is cranking 
  11. A fault is not currently present and may be an intermittent condition.
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