GMC 1995 Safari Owner's Manual page 311

Starter Switch
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.
PARK
(P)
or NEUTRAL
(N).
If the starter works in any other position,
your vehicle needs service.
3. Try to start the engine in each gear. The starter should work only in
Brake-Transmission Shift Interlock
-
BTSI
1. Before you start, be sure you have enough room around the vehicle. It
2. Firmly apply the parking brake (see "Parking Brake" in the Index if
should be parked on a level surface.
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.