1997 GMC Sonoma Owner's Manual - Page 366

Starter Switch Check I I I Brake-Transmission Shift Interlock (BTSI) Check (Automatic Transmission) When you aredoing this check, the vehicle could move suddenly. If it does, you or others could be injured. Follow the steps below. 1. Before you start, be sure you have enough room around the vehicle. 2. Firmly apply both the parking brake (see "Parking Brake" in the Index if necessary) and the regular brake. NOTE: Do not use the accelerator pedal, and be ready to turn off the engine immediately if it starts. 3. On automatic transmission vehicles, try to start the engine in each gear. The startershould work only in PARK (P) or NEUTRAL (N). If the starter works in any other position, your vehicle needs service. On manual transmission vehicles, put the shift lever in NEUTRAL (N), push the clutch down halfway and try to start the engine. The starter should work only when the clutch is pushed down all the way to the floor. If the starter works when the clutch isn't pushed all the way down, your vehicle needs service. 7-5b - / When you are doing this check, the vehicle could move suddenly. If it does, or others could be you injured. Follow the steps below. 1. Before you start, be sure you have enough room around the vehicle. It should be parked on a level surface. 2. Firmly apply the parking brake (see "Parking Brake" in the Index if necessary). NOTE: Be ready to apply the regular brake immediately if the vehicle begins to move. 3. With the engine off, turn the key to the RUN position, but don't start the engine. Without applying the regular brake, try to move the shift lever out of PARK (P) with normal effort. If the shift lever moves out of PARK (P), your vehicle's BTSI needs service.