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 to the shift lock control
solenoid though 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 powertrain control module (PCM) 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 brake light switch. |
The shift lock control solenoid is permanently ground, when the BCM supplies
voltage to the automatic transmission shift lock control solenoid the solenoid energizes,
releasing the mechanical lock. This allows the driver to move the shift lever out
of the PARK position. When the ignition is in the ACCY position the transmission position
is not a required input for shift lock control operation.
Vehicles equipped with VTi variable transmission in cold weather temperatures
below -25°C (-13°F) the PCM will send a class 2 message
to the BCM preventing the operation of the shift lock control solenoid and the temperature
gage light will flash. Once the transmission has warmed above -25°C (-13°F)
the temperature gage light will stop flashing and normal shift lock control operation
will resume.
