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

WARNING: This page is about a different car, the 2006 Mercury Milan, 2006 Lincoln Zephyr, and 2006 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

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.