For 1990-2009 cars

The brake/transmission shift interlock requires that the brake pedal be depressed and the ignition switch be placed in the RUN or START position before the transmission may be shifted from the park position. When the transmission is shifted from the park position and the ignition switch is in RUN or START, current flows from the GAUGES Fuse 9, through the stoplamp switch, through the brake/transmission shift interlock solenoid, and through the contacts of the park/neutral position switch (closed in park/neutral) to ground G110. The solenoid is energized preventing the transmission from being shifted into another gear. When the brake pedal is depressed, the normally-closed contacts in the stoplamp switch open. Current flow is interrupted and the brake/transmission shift interlock solenoid is de-energized. The transmission may then be shifted to another gear. Once the transmission is shifted to another gear (except neutral), the contacts in the park/neutral switch are open and no current can flow to energize the solenoid when the brake pedal is released.