Pinpoint Test A: The Shift Interlock System Does Not Release/Lock Correctly

A1 CHECK THE POWER SUPPLY TO THE BRAKE SHIFT INTERLOCK ACTUATOR
NOTE: Test Step A1 diagnoses why the brake shift interlock system does not release correctly.
- Key in OFF position.
- Disconnect: Brake Shift Interlock Actuator.
- Key in ON position.
- Apply the brake pedal.
- Measure the voltage between brake shift interlock actuator pin 3 harness side and ground.
  
  Fig 1: Checking Power Supply To Brake Shift Interlock Actuator
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
Yes : INSTALL a new brake shift interlock actuator. REFER to BRAKE SHIFT INTERLOCK ACTUATOR in this article. TEST the system for normal operation.

No : REPAIR circuit. RECONNECT all components. TEST the system for normal operation. If the shift interlock system does not lock correctly, GO to A2.
A2 CHECK THE POWER SUPPLY TO THE BRAKE SHIFT INTERLOCK ACTUATOR
- Key in OFF position.
- Disconnect: Brake Shift Interlock Actuator.
- Key in ON position.
- Measure the voltage between brake shift interlock actuator pin 1 harness side and ground.
  
  Fig 2: Checking Power Supply To Brake Shift Interlock Actuator
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
Yes : GO to A3.

No : REPAIR circuit. RECONNECT all components. TEST the system for normal operation.
A3 CHECK CIRCUIT FOR AN OPEN
- Key in OFF position.
- Measure the resistance between brake shift interlock actuator pin 2 harness side and ground.
  
  Fig 3: Checking Circuit For An Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : INSTALL a new brake shift interlock actuator. REFER to BRAKE SHIFT INTERLOCK ACTUATOR in this article. TEST the system for normal operation.

No : REPAIR circuit. RECONNECT all components. TEST the system for normal operation.