The automatic transmission controller shift lever locks
in PARK when the brake transmission shift interlock (BTSI) solenoid is energized.
When you apply the brake, the BTSI solenoid is de-energized allowing the
automatic transmission controller shift lever to be moved while depressing
the park lock release button on the knob .
The park lock solenoid energizes when the ignition switch is in the
OFF position preventing the park lock release button on the shift knob from
being depressed.
The following components are involved in the BTSI circuit:
| • | The underhood fuse block |
| • | The park/neutral position (PNP) and backup lamp switch |
| • | The TCC/stop lamp switch |
| • | The automatic transmission controller assembly |
The BTSI solenoid is energized when all of the following conditions
exist:
| • | The ignition switch is in the RUN or the START position. |
| • | The automatic transmission controller shift lever is in PARK or
NEUTRAL. |
| • | The brake pedal is released. |
Once the BTSI solenoid is energized, the transmission shift lever is
locked in PARK.
The BTSI portion of the TCC/stop lamp switch (pin E and pin F)
is closed with the brake pedal released. Actuate the brake pedal in order
to open the switch. Opening the switch causes the BTSI solenoid to de-energize
in order to unlock the automatic transmission controller shift lever. The
BTSI circuit is not active with the ignition switch in the OFF position. The
battery must be disconnected in order to de-energize the park lock solenoid
to allow the shift knob button to be depressed allowing the shift lever to
be moved to facilitate for towing.
