Bulletin No.: 03-07-30-043A
Date: May 25, 2006
Information Regarding Automatic Transmission Shift Lock Control Function
2007 and Prior Passenger Cars and Trucks (Including Saturn)
2007 and Prior HUMMER H2, H3
2005-2007 Saab 9-7X
with Automatic Transmission
This bulletin is being revised to add models and model years. Please discard Corporate Bulletin Number 03-07-30-043 (Section 07 - Transmission/Transaxle). This bulletin is being issued to better explain how the Automatic Transmission Shift Lock Control (formerly known as Brake Transmission Shift Interlock (BTSI)) feature is intended to operate. Revised wording regarding the shift lock control system began appearing in the Owner Manuals beginning with the 2004 model year.
The shift lock control feature was intended to prevent drivers from shifting out of Park with the vehicle running without the brakes applied. However, if the ignition switch is in the Accessory (ACC) position, it may be possible on some vehicles to move the shift lever out of Park WITHOUT first activating the brake.
The shift lock control system is ONLY active when the ignition switch is in the RUN or ON position. This means that when the ignition switch is in the RUN or ON position, the shift lever cannot be moved out of the Park position without activating the brake.
Some owners may feel that the shift lock control system prevents an unattended child from moving the vehicle. Please stress to owners, as stated in the Owner Manual, that children should NEVER be left unattended in a vehicle, even if the ignition key has been removed from the vehicle.
Automatic Transmission Shift Lock Control Description and Operation
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 thew following components:
- The automatic transmission shift lock control solenoid
- The body control module (BCM)
- The engine control module (ECM)
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 ECM sends an input via GMLAN serial data to the BCM when the transmission control module (TCM) indicates the transmission is in the PARK position
- The BCM receives a brake applied input from the brake light 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. The energized solenoid allows the driver to move the shift lever out of the PARK position. When the brake pedal is not applied, the BCM turns the control voltage output of the shift lock control solenoid OFF, de-energizing the shift lock control solenoid. When the transmission is in the PARK position, the de-energized shift lock control solenoid will prevent shifting as the lever is mechanically locked in the PARK position. During remote start operation the BCM will de-energize the automatic transmission shift lock control circuit, locking the shift lever in the PARK position.