The Supplemental Inflatable Restraint (SIR) supplements the protection offered by the driver's seat belt by deploying an air bag from the center of the steering wheel during certain frontal crashes. The air bag deploys when the vehicle is involved in a frontal crash of sufficient force up to 30 degrees off the centerline of the vehicle. The steering wheel is collapsible and should be inspected after an accident whether or not a deployment has occurred.

The SIR system components in the steering wheel and column are the driver inflator module and SIR coil assembly.

The Brake Transmission Shift Lock Control Solenoid prevents the transmission from shifting when it is energized. The Brake Transmission Shift Lock Control Solenoid is energized when the Park/Neutral Position Switch is in Park and the brake pedal is depressed (i.e., the Brake Transmission Shift Interrupt (BTSI) Switch is closed).

Battery voltage is applied to the Brake Transmission Shift Lock Control Solenoid when the ignition switch is in the RUN position, through the Park/Neutral Position Switch and the BTSI Switch using circuits 341, 434, 443, and 1135. The Brake Transmission Shift Lock Control Solenoid is grounded circuit 150 to Splice Pack #202, SP202.

Constant battery voltage is applied to the Brake Transmission Shift Lock Control Solenoid indicator through circuit 240. The Brake Transmission Shift Lock Control Solenoid indicator is grounded through the Body Control Computer using circuit 8.

The Column Lock system uses a remote mounted Ignition Switch. The Column Lock is controlled by the BCM, the BCM must see a valid Vats key and at least ACC position of the ignition switch to unlock the Column. The BCM must see an indication of ignition switch in the OFF position (no ACC or RUN signals) and indication that the key has been removed from the ignition switch to lock the column once these conditions have been met. The BCM waits two seconds to activate the column locking motor to the lock position. As a safeguard to avoid an unwanted locking of the column there is a Key-Out switch which is only closed when the key is removed, this switch must be closed to provide the ground path necessary to run the column lock motor in the lock direction.

There is a feedback switch that indicates to the BCM when the column is unlocked. Should this transition from lock to unlock not occur the BCM must assume the column is still locked. It will then not communicate the proper message to the PCM, and the PCM will shut off the engine if the vehicle speed is detected. This will prohibit the vehicle from being driven with a locked column.