Automatic Transmission Shift Lock Control Description

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 consist of the following components:
- The automatic transmission shift lock control solenoid.
- The automatic transmission shift lock control switch.
- The automatic transmission shift lock control unlock switch.
- The stoplamp switch.
- The Body Control Module (BCM).
- The lifting magnet.
When the brake pedal is pressed, the stop lamp switch supplies B+ to the automatic transmission shift lock control solenoid. The automatic transmission shift lock control solenoid is grounded through the automatic transmission shift lock control switch. The automatic transmission shift lock control solenoid energizes allowing the operation of the shift lever.

Brake to Shift Indicator
The brake to shift indicator is a light that reminds the driver to press the brake pedal before attempting to move the shift lever out of the PARK position. The system consist of the following components:
- The stoplamp switch.
- The Body Control Module (BCM).
- The brake to shift indicator.
When the ignition in the ON position, battery positive voltage (B+)is supplied to the BRAKE TO SHIFT indicator. The BCM grounds the BRAKE TO SHIFT indicator when the ignition is in the ON position, turning the BRAKE TO SHIFT indicator ON. When the brake pedal is pressed, the BCM receives B+ from the stop lamp switch. The BCM responds by removing the ground signal from the BRAKE TO SHIFT indicator, turning OFF the BRAKE TO SHIFT indicator. This informs the driver that they can now operate the transmission shift lever. The BCM will turn the BRAKE TO SHIFT indicator back ON when the automatic transmission shift lock control switch is returned to the PARK position.

Sport/Economy Mode Operation
The sport mode will produce a firmer shift and delay part throttle upshifts. The sport mode can be activated anytime the ignition is in the RUN position by pressing the Sport/Economy mode switch. Selecting the sport mode will illuminate the sport mode indicator on the instrument panel and increase the line pressure. The transmission will remain in sport mode unless the sport and or economy switch is pressed or the ignition is turned to the OFF position. The transmission will normally default to economy mode.

Winter Mode Operation
The winter mode allows the transmission to start off in third gear. Third gear take off reduces the torque to the rear wheels and improves traction during slippery conditions. The winter mode can be activated only if all of the following conditions are met:
- The transmission control must be in Drive (D).
- The vehicle speed must be below 10 km (6 mph).
- The transmission fluid temperature must be below 130°C (266°F).
- The throttle position must be below 7%.
To activate the winter mode press the snowflake switch (first and second gear block switch) located next to the transmission control. The winter mode indicator will illuminate on the instrument panel.
The winter mode will be deactivated by any one of the following:
- The transmission control is placed in a lower gear than Drive (D).
- The vehicle speed exceeds 50 km (32 mph).
- The transmission fluid temperature rises above 130°C (266°F).
- Pressing the snowflake switch.
- The kickdown switch is activated.

Limp Home Mode Description
When the ignition is switch to the RUN position the TCM performs a functional check of the solenoid valves, switches and sensors. If a problem is detected at any of the TCM inputs the TCM will enter the limp home mode. In the limp home mode the operator can manually select the gears regardless of vehicle speed. Care should be taken not to downshift and over rev the engine.