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

A1 TEST THE BRAKE LIGHTS
- Apply the brake pedal and view the brake lights.
- Do the brake lights illuminate?
Yes : GO to A2.

No : REFER to EXTERIOR LIGHTING .
A2 TEST SHIFT INTERLOCK ACTUATOR POWER CIRCUIT
- Disconnect: Floor Shifter Harness Connector C3245.
- Key in ON position.
- Measure the voltage between floor shifter harness connector C3245-1, vehicle harness side and ground, while applying the brake pedal.
  
  Fig 1: Testing Shift Interlock Actuator Power Circuit
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
Yes : GO to A3.

No : REPAIR the circuit. TEST the system for normal operation.
A3 TEST SHIFT INTERLOCK ACTUATOR GROUND CIRCUIT
- Key in OFF position.
- Measure the resistance between floor shifter harness connector C3245-4, vehicle harness side and ground.
  
  Fig 2: Testing Shift Interlock Actuator Ground Circuit
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : INSTALL a new selector lever. Refer to SELECTOR LEVER

No : REPAIR the circuit. TEST the system for normal operation.