Jul 132016
 

1997 Mercury Grand MarquisHave a master cylinder leak. Cant get the car our of park. Is there a safety or is it an unrelated issue?


RESPONSE

Unrelated issue. The park brake shift interlock switch is electronic and the brakes are hydraulic. A leak in the hydraulics will not affect the brake interlock switch.

Shift Interlock System

The brake/shifter interlock system operates as follows:

  • All vehicles use a brake shift interlock mechanism consisting of a shift lock actuator (3Z719) attached to the steering column tube (3514).
  • This mechanism prevents shifting the transmission out of the PARK position unless the brake pedal (2455) is applied.
  • When ignition switch is turned to the RUN position, the shift lock actuator is energized, locking shifter in PARK position.
  • When brake pedal is applied and the stoplight switch (13480) is activated, the brake shift lock actuator is deactivated and the transmission range selector lever can be moved out of the PARK position.

Brake/Shift Interlock System Cleaning and Inspection

  1. Turn ignition switch to RUN.
  1. Verify that transmission range selector lever is in PARK.
  1. Without brake pedal applied, verify that transmission range selector lever cannot be shifted from PARK.
  1. Apply brake pedal. Verify that transmission range selector lever can be shifted from PARK.
  1. Shift transmission range selector lever to REVERSE.
  1. Verify that ignition switch cannot be turned to the LOCK position.
  1. Shift transmission range selector lever to PARK.
  1. Verify that ignition switch can be turned to the LOCK position.
  1. If shift-lock system is not operating as specified, refer to Diagnosis and Testing.

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