Automatic Transmission Shift Lock Control Description and
Operation
The automatic transmission park lock control system is a safety
device that prevents an inadvertent shift out of PARK. The driver
must press the brake pedal before moving the park lever out of the
PARK position. The system consists of the following components:
• |
The automatic transmission
park lock solenoid (serviced as the automatic transmission shift
lock actuator), is located within the floor shift control
assembly. |
• |
The body control module, which
controls the voltage supply circuit of the park lock control
solenoid. |
• |
The engine control
module. |
The body control module controls the voltage to the park lock
control solenoid through the park lock control solenoid controlled
voltage circuit. The following conditions must be met before the
body control module will supply voltage to the park lock
solenoid:
• |
The ignition is in the ON
position. |
• |
The engine control module
sends an input via GMLAN serial data to the body control module
indicating the transmission is in the PARK position. |
• |
The body control module
determines the brake pedal is applied according the brake pedal
position. |
Since the park lock control solenoid is permanently grounded,
the body control module supplies voltage to the automatic
transmission park lock control solenoid, unlocking the park lever
allowing the driver to move the park lever out of the PARK position
as the solenoid energizes. When the brake pedal is not applied, the
body control module turns the control voltage output of the park
lock control solenoid OFF, de-energizing the park lock control
solenoid. The de-energized solenoid mechanically locks the park
lever in the PARK position.
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