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 powertrain control module (PCM) |
The body control module (BCM) controls the voltage supply circuit of the shift
lock control solenoid. The following conditions must be met before the BCM will supply
battery voltage to the shift lock control solenoid:
| • | The ignition is in the ON position. |
| • | The PCM sends a class 2 message to the BCM indicating the transmission
is in the PARK position. |
| • | The PCM receives a brake applied input from the stop lamp switch and sends
a class 2 message to the BCM indicating the brakes are applied. |
With the above conditions met, the BCM supplies battery voltage to the shift
lock control solenoid. Since the solenoid is permanently grounded, the solenoid energizes
allowing the driver to move the shift lever out of the PARK position. When the brake
pedal is not applied, the BCM turns OFF the controlled voltage output to the shift
lock control solenoid, de-energizing the shift lock control solenoid. The de-energized
solenoid mechanically locks the shift lever in the PARK position.
