Automatic Transmission Shift Lock Control System
The automatic transmission shift lock control system is a safety device that
prevents an inadvertent shift out of PARK when the engine is running. The driver must
press the brake pedal before moving the shift lever out of the PARK position. The
system consists of the following components:
• | The automatic transmission shift lock control solenoid |
• | The body control module (BCM) |
• | The transmission control module (TCM) |
The BCM controls the voltage to the shift lock control solenoid through the
shift lock control solenoid controlled voltage circuit. The following conditions must
be met before the BCM will supply voltage to the shift lock control solenoid:
• | The ignition is in the ON position. |
• | The TCM sends a class 2 message to the BCM indicating the transmission
is in the PARK position. |
• | The BCM receives a brake applied input from the stop lamp switch. |
Since the shift lock control solenoid is permanently grounded, the BCM supplies
voltage to the automatic transmission shift lock control solenoid, releasing the mechanical
lock on the shift lever as the solenoid energizes. This allows the driver to move
the shift lever out of the PARK position. When the brake pedal is not applied, the
BCM switches the ground of the shift lock control solenoid OFF, de-energizing the
shift lock control solenoid. The de-energized solenoid mechanically locks the shift
lever in the PARK position.