Shift Interlock System: Other GMC Safari II

BRAKE TRANSMISSION INTERLOCK SOLENOID

Note. Brake Transmission Shift Interlock (BTSI) solenoid may also be known as shift interlock actuator.

Gear selector cannot be moved from Park without depressing brake pedal if ignition is on. When pressure is applied to brake pedal, BTSI solenoid is de-energized to release gear selector from Park. Brakelight switch interrupts circuit to mechanically unlock gear selector by de-energizing BTSI solenoid. See WIRING DIAGRAMS .

PARK LOCK CABLE

Gear selector is locked in Park when ignition switch is in LOCK position. With ignition on, gear selector is allowed movement to desired position. Ignition key cannot be removed until gear selector is returned to Park. Park lock cable is located on steering column. (Scheme 6)

Scheme 6

BTSI CONTROL INOPERATIVE

Note. Ensure Park/Neutral Position (PNP) switch is adjusted properly. See appropriate AUTOMATIC TRANSMISSION SERVICING article in TRANSMISSION SERVICING. PNP switch my also be referred to as Transaxle Range (TR) switch. Verify system operation after performing any repairs. See SYSTEM OPERATION CHECK under TROUBLE SHOOTING.

"L" & "M" Series

1. Check for open TURN B/U (20-amp) fuse located in instrument panel fuse block. If fuse is open, go to next step. If fuse is okay, go to step 3 .
2. Locate and repair short to ground in BTSI system circuit. Replace TURN B/U (20-amp) fuse.
3. Disconnect Park/Neutral Position (PNP) switch harness connector. Turn ignition on. Using test light connected to ground, probe ignition feed circuit (Pink wire) at PNP switch harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 5 .
4. Using fused jumper wire, jumper Pink wire and Light Green wire together at PNP switch harness connector. If gear selector locks in Park, go to step 6 . If gear selector does not lock in Park, go to step 7 .
5. Repair open in ignition feed circuit (Pink wire) between PNP switch and TURN B/U (20-amp) fuse.
6. Replace PNP switch.
7. Reconnect PNP switch harness connector. Disconnect brakelight switch harness connector. Using test light connected to ground, probe ignition feed circuit (Light Green wire) at brakelight switch harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 9 .
8. Using fused jumper wire, jumper Light Green wire and Dark Green/White wire together at brakelight switch. If gear selector remains unlocked in Park, go to step 10 . If gear selector locks in Park, go to step 11 .
9. Repair open in ignition feed circuit (Light Green wire) between PNP switch and brakelight switch.
10. Reconnect brakelight switch harness connector. Disconnect BTSI solenoid harness connector. Using test light connected to ground, probe ignition feed circuit (Dark Green/White wire) at BTSI solenoid harness connector. If test light illuminates, go to step 12 . If test light does not illuminate, go to step 13 .
11. Replace brakelight switch.
12. Connect test light between terminals of BTSI solenoid harness connector. If test light illuminates, go to step 14 . If test light does not illuminate, go to step 15 .
13. Repair open in ignition feed circuit (Dark Green/White wire) between brakelight switch and BTSI solenoid.
14. Replace BTSI solenoid.
15. Repair open in ground circuit between BTSI solenoid and chassis ground.

"U" Series

1. Place gear selector in Park. Turn ignition on. Using test light connected to ground, backprobe ignition feed circuit (Pink wire) at brakelight switch harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 3 .
2. Using test light connected to ground, backprobe BTSI solenoid ignition feed circuit (Dark Green/White wire) at brakelight switch harness connector. If test light illuminates, go to step 4 . If test light does not illuminate, go to step 5 .
3. Repair faulty connection or open in ignition feed circuit between brakelight switch and IGN 1 (10-amp) fuse located in instrument panel fuse block.
4. Using test light connected to ground, backprobe ignition feed circuit (Dark Green/White wire) at BTSI solenoid harness connector. If test light illuminates, go to step 6 . If test light does not illuminate, go to step 7 .
5. Check for faulty connection at brakelight switch. Repair as necessary. If connection is okay, adjust or replace brakelight switch.
6. Using test light connected to ground, backprobe Black wire at BTSI solenoid harness connector. If test light illuminates, go to step 9 . If test light does not illuminate, go to step 8 .
7. Repair faulty connection or open in ignition feed circuit (Dark Green/White wire) between brakelight switch and BTSI solenoid.
8. Check for faulty connection at BTSI solenoid. Repair as necessary. If connection is okay, replace BTSI solenoid.
9. Disconnect Transaxle Range (TR) switch. Using test light connected to ground, probe Orange/Black wire at TR switch harness connector. If test light illuminates, go to step 11 . If test light does not illuminate, go to next step.
10. Repair faulty connection or open in ground circuit (Orange/Black wire) between BTSI solenoid and TR switch.
11. Using test light connected to battery positive terminal, probe ground circuit (Black/White wire) at TR switch harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
12. Check for faulty connection at TR switch. Repair as necessary. If connection is okay, adjust or replace TR switch.
13. Check for faulty connection or open in ground circuit (Black/White wire) between TR switch and chassis ground. Repair as necessary.

1. Turn ignition on. Disconnect BTSI solenoid harness connector. If gear selector can be moved from Park, go to next step. If gear selector cannot be moved from Park, go to step 3 .
2. Disconnect brakelight switch harness connector. Using test light connected to ground, probe BTSI solenoid ignition feed circuit (Dark Green/White wire) at brakelight switch harness connector. If test light illuminates, go to step 4 . If test light does not illuminate, go to step 5 .
3. Remove BTSI solenoid assembly. If gear selector can be moved from Park, go to step 6 . If gear selector cannot be moved from Park, diagnose mechanical malfunction by symptom. See SYMPTOM DIAGNOSIS under TROUBLE SHOOTING in appropriate OVERHAUL article.
4. Repair short to voltage in BTSI solenoid ignition feed circuit (Dark Green/White wire) between brakelight switch and BTSI solenoid.
5. Replace brakelight switch.
6. Replace BTSI solenoid.

1. Place gear selector in Park. Disconnect BTSI solenoid harness connector. Turn ignition on. If gear selector can be moved from Park, go to step 9 . If gear selector cannot be moved from Park, go to next step.
2. Disconnect BTSI control rod. If gear selector can be moved from Park, go to next step. If gear selector cannot be moved from Park, go to step 4 .
3. Adjust or replace BTSI solenoid.
4. Disconnect shift cable at steering column. If gear selector can be moved from Park, go to next step. If gear selector cannot be moved from Park, go to step 7 .
5. Reconnect shift cable at steering column. Disconnect shift cable at transaxle. If gear selector can be moved from Park, go to next step. If gear selector cannot be moved from Park, go to step 8 .
6. Repair transaxle internal linkage.
7. Repair linear shift assembly in steering column.
8. Replace shift cable.
9. Using test light connected to ground, probe BTSI solenoid ignition feed circuit (Dark Green/White wire) at BTSI solenoid harness connector. Depress brake pedal. If test light remains illuminated, leave test light connected and go to next step. If test light is not illuminated, go to step 3 .
10. Disconnect brakelight switch harness connector. If test light remains illuminated, go to next step. If test light is not illuminated, go to step 12 .
11. Repair short to battery voltage in ignition feed circuit (Dark Green/White wire) between BTSI solenoid and brakelight switch.
12. Adjust or replace brakelight switch.

Note. Brake Transmission Shift Interlock (BTSI) solenoid may also be known as shift interlock actuator.

Actuator is located on steering column. (Scheme 7) Pull locking tab outward from block side of actuator. (Scheme 8) Ensure gear selector is in Neutral. Press on adjuster block to compress internal adjuster spring and engage adjuster teeth. Slide adjuster block as far away from solenoid as possible. Move gear selector into Park. Push locking tab back into adjuster block. Ensure proper operation of system.

Scheme 7

Scheme 8

1. Lift cable lock button. Move gear selector into Park. Snap cable connector into shifter base. Ensure ignition switch is in ON position.
2. Snap cable housing into ignition switch inhibitor. Turn ignition key to LOCK position. Snap cable end onto park lock lever pin. Remove slack from cable connector. Snap cable connector lock button down.