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Home/Chevrolet/Blazer/Chevrolet Blazer S15 facelift (1998-2005)/Repair manual/Automatic Trans/Shift Interlock Systems: Diagnosis
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Shift Interlock Systems: Diagnosis Chevrolet Blazer S15 facelift

Automatic Trans ~2789 words

DIAGNOSTIC STARTING POINT

Begin the system diagnosis by reviewing DESCRIPTION & OPERATION . Reviewing the description and operation information will help you determine the correct symptom diagnostic procedure when a malfunction exists. Reviewing the description and operation information will also help you determine if the condition described by the customer is normal operation. See SYMPTOM DIAGNOSIS in order to identify the correct procedure for diagnosing the system and where the procedure is located.

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the shift lock control system. Inspect easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

  1. Park Lock Solenoid Inoperative
  2. Shift Lever Does Not Move With Brake Pedal Depressed
  3. Shift Lever Can Be Moved Without Brake Pedal Depressed

See appropriate test under SYMPTOM TESTS .

SYMPTOM TESTS

CAUTIONUse caution when probing fuses or junction blocks, or any connectors. Damage may result to connector or terminal if probe being used is too large. Electronic modules are sensitive to static electrical charges. If exposed to these charges, damage may result.
SymptomTest
Park Lock Solenoid Inoperative (Floor Shift)A
Shift Lever Does Not Move With Brake Pedal Depressed (Column Shift)B
Shift Lever Does Not Move with Brake Pedal Depressed (Floor Shift)C
Shift Lever Can Be Moved Without Brake Pedal Depressed (Column Shift)D
Shift Lever Can Be Moved Without Brake Pedal Depressed (Floor Shift)E

SYMPTOM TEST INDEX

TEST A: PARK LOCK SOLENOID INOPERATIVE (FLOOR SHIFT)

Note. For circuit reference, see CONNECTOR IDENTIFICATION and WIRING DIAGRAMS .

  1. Did you review the DESCRIPTION and OPERATION and perform the necessary inspections? If so, go to next step. If not, see «DESCRIPTION & OPERATION»(ref-135819-S20023002132002022500000) .
  2. Place the gearshift lever in the Park position. Turn ignition switch to the OFF position. Depress the brake pedal. Attempt to move the gearshift lever out of the Park position. Does the gearshift lever move out of the Park position? If so, go to next step. If not, check for intermittent condition. See «SYMPTOM DIAGNOSIS»(ref-135819-S02529281672002022500000) under TROUBLE SHOOTING.
  3. Disconnect the park lock solenoid. See «STEERING COLUMN PARK LOCK SOLENOID (FLOOR SHIFT)»(ref-135819-S05550692222002022500000) under REMOVAL & INSTALLATION. Press and hold the brake pedal. Attempt to move the gearshift lever out of the Park position. Does the gearshift lever move out of the Park position? If so, go to next step. If not, go to step 5 .
  4. Inspect park lock solenoid for poor connections. Did you find and correct the condition? If so, go to step 7 . If not, go to step 6 .
  5. Repair the stoplamp switch voltage supply circuit (Light Green/Black wire) for a short to voltage. After repairs, go to step 7 .
  6. Replace the park lock solenoid. See «FLOOR SHIFT CONTROL»(ref-135819-S29564780212002022600000) under REMOVAL & INSTALLATION. After repairs, go to next step.
  7. Operate the system in order to verify the repair. Did you find and correct the condition? If so, system is okay. If not, go to step 2 .

TEST B: GEARSHIFT LEVER DOES NOT MOVE WITH BRAKE PEDAL DEPRESSED (COLUMN SHIFT)

Note. For circuit reference, see CONNECTOR IDENTIFICATION and WIRING DIAGRAMS .

  1. Did you review the DESCRIPTION and OPERATION and perform the necessary inspections? If so, go to next step. If not, see «DESCRIPTION & OPERATION»(ref-135819-S20023002132002022500000) .
  2. Turn ignition switch to the ON position. Depress the brake pedal. Attempt to move the gearshift lever out of the Park position. Does the gearshift lever move out of the Park position? If so, check for an intermittent condition. See «SYMPTOM DIAGNOSIS»(ref-135819-S02529281672002022500000) under TROUBLE SHOOTING. If not, go to next step.
  3. Turn the ignition switch to the OFF position. Disconnect the stoplamp switch. Turn the ignition switch to the ON position. Press and hold the brake pedal. Attempt to move the gearshift lever out of the Park position. Does the gearshift lever move out of the Park position? If so, go to step 5 . If not, go to next step.
  4. Turn the ignition switch to the OFF position. Disconnect the shift lock solenoid. See «SHIFT LOCK SOLENOID (COLUMN SHIFT)»(ref-135819-S23940823032002022600000) under REMOVAL & INSTALLATION. Turn the ignition switch to the ON position. Press and hold the brake pedal. Attempt to move the gearshift lever out of the Park position. Does the gearshift lever move out of the Park position? If so, go to step 7 . If not, go to step 6 .
  5. Inspect the stoplamp switch for poor connections. Did you find and correct the condition? If so, go to step 10 . If not, go to step 8 .
  6. Inspect the shift lock solenoid for poor connections. Did you find and correct the condition? If so, go to step 10 . If not, go to step 9 .
  7. Repair the short to voltage in the shift lock solenoid voltage supply circuit (Dark Green/White wire). After repairs, go to step 10 .
  8. Replace the stoplamp switch. See «STOPLAMP SWITCH»(ref-135819-S14984344712002022600000) under REMOVAL & INSTALLATION. After repairs, go to step 10 .
  9. Replace the shift lock solenoid. See «SHIFT LOCK SOLENOID (COLUMN SHIFT)»(ref-135819-S23940823032002022600000) under REMOVAL & INSTALLATION. After repairs, go to next step.
  10. Operate the system in order to verify the repair. Did you find and correct the condition? If so, system is okay. If not, go to step 2 .

TEST C: GEARSHIFT LEVER DOES NOT MOVE WITH BRAKE PEDAL DEPRESSED (FLOOR SHIFT)

Note. For circuit reference, see CONNECTOR IDENTIFICATION and WIRING DIAGRAMS .

  1. Did you review the DESCRIPTION and OPERATION and perform the necessary inspections? If so, go to next step. If not, see «DESCRIPTION & OPERATION»(ref-135819-S20023002132002022500000) .
  2. Turn ignition switch to the ON position. Depress the brake pedal. Attempt to move the gearshift lever out of the Park position. Does the gearshift lever move out of the Park position? If so, check for an intermittent condition. See «SYMPTOM DIAGNOSIS»(ref-135819-S02529281672002022500000) under TROUBLE SHOOTING. If not, go to next step.
  3. Turn the ignition switch to the OFF position. Disconnect the stoplamp switch. Turn the ignition switch to the ON position. Press and hold the brake pedal. Attempt to move the gearshift lever out of the Park position. Does the gearshift lever move out of the Park position? If so, go to step 10 . If not, go to next step.
  4. Turn the ignition switch to the OFF position. Disconnect the shift lock solenoid. See «FLOOR SHIFT CONTROL»(ref-135819-S29564780212002022600000) under REMOVAL & INSTALLATION. Turn the ignition switch to the ON position. Press and hold the brake pedal. Attempt to move the gearshift lever out of the Park position. Does the gearshift lever move out of the Park position? If so, go to step 13 . If not, go to next step.
  5. Turn the ignition switch to the OFF position. Connect a test light between ground and the stoplamp switch voltage supply circuit (Light Green/Black wire) at the park lock solenoid. See «STEERING COLUMN PARK LOCK SOLENOID (FLOOR SHIFT)»(ref-135819-S05550692222002022500000) under REMOVAL & INSTALLATION. Turn the ignition switch to the ON position. Does the test light illuminate? If so, go to next step. If not, go to step 7 .
  6. Turn the ignition switch to the OFF position. Connect a test light between the stoplamp switch voltage supply circuit (Light Green/Black wire) and the ground circuit (Black wire) at the park lock solenoid. Turn the ignition switch to the ON position. Does the test light illuminate? If so, go to step 11 . If not, go to step 14 .
  7. Turn the ignition switch to the OFF position. Connect a test light between ground and the PNP switch park signal circuit (Light Green wire) at the BTSI fuse. Turn the ignition switch to the ON position. Does the test light illuminate? If so, go to step 15 . If not, go to next step.
  8. Turn the ignition switch to the OFF position. Connect a test light between ground and the ignition feed circuit (Pink wire) at the PNP switch. Turn the ignition switch to the ON position. Does the test light illuminate? If so, go to next step. If not go to step 16 .
  9. Turn the ignition switch to the OFF position. Connect a test light between ground and the park signal circuit (Light Green wire) at the PNP switch. Turn the ignition switch to the ON position. Does the test light illuminate? If so, go to step 17 . If not, go to step 12 .
  10. Inspect the stoplamp switch for poor connections. Did you find and correct the condition? If so, go to step 21 . If not, go to step 18 .
  11. Inspect the shift lock solenoid for poor connections. Did you find and correct the condition? If so, go to step 21 . If not go to step 19 .
  12. Inspect for proper PNP switch adjustment. See appropriate AUTOMATIC article in AUTOMATIC TRANSMISSIONS. Inspect the PNP switch for poor connections. Did you find and correct the condition? If so, go to step 21 . If not, go to step 20 .
  13. Repair the short to voltage in the shift lock solenoid voltage supply circuit (Dark Green/White wire). After repairs, go to step 21 .
  14. Repair the open in the shift lock solenoid ground circuit (Black wire). After repairs, go to step 21 .
  15. Repair the open in the stoplamp switch voltage supply circuit (Light Green/Black wire). After repairs, go to step 21 .
  16. Repair the open in the PNP switch ignition feed circuit (Pink wire). After repairs, go to step 21 .
  17. Repair the open in the PNP switch park signal circuit (Light Green wire). After repairs, go to step 21 .
  18. Replace the stoplamp switch. See «STOPLAMP SWITCH»(ref-135819-S14984344712002022600000) under REMOVAL & INSTALLATION. After repairs, go to step 21 .
  19. Replace the shift lock solenoid assembly. See «FLOOR SHIFT CONTROL»(ref-135819-S29564780212002022600000) under REMOVAL & INSTALLATION. After repairs, go to step 21 .
  20. Replace the PNP switch. See appropriate AUTOMATIC article in AUTOMATIC TRANSMISSIONS. After repairs, go to next step.
  21. Operate the system in order to verify the repair. Did you find and correct the condition? If so, system is okay. If not, go to step 2 .

TEST D: GEARSHIFT LEVER CAN BE MOVED WITHOUT BRAKE PEDAL DEPRESSED (COLUMN SHIFT)

Note. For circuit reference, see CONNECTOR IDENTIFICATION and WIRING DIAGRAMS .

  1. Did you review the DESCRIPTION and OPERATION and perform the necessary inspections? If so, go to next step. If not, see «DESCRIPTION & OPERATION»(ref-135819-S20023002132002022500000) .
  2. Apply the parking brake and block the wheels. Turn the ignition switch to the ON position. Attempt to move the gearshift lever out of the Park position. Does the gearshift lever move out of the Park position? If so, go to next step. If not, condition is intermittent. See «SYMPTOM DIAGNOSIS»(ref-135819-S02529281672002022500000) under TROUBLE SHOOTING.
  3. Turn the ignition switch to the OFF position. Ensure gearshift lever is in the Park position. Connect a test light between ground and the stoplamp switch voltage supply circuit (Light Green/Black wire) at the BTSI fuse. Turn the ignition switch to the ON position. Does the test light illuminate? If so, go to next step. If not, go to step 8 .
  4. Connect a test light between ground and the stoplamp switch voltage supply circuit (Light Green/Black wire). Does the test light illuminate? If so, go to next step. If not, go to step 14 .
  5. Connect a test light between ground and stoplamp switch output circuit (Dark Green/White wire). Press and release the brake pedal several times. Does the test light turn ON and OFF with the brake pedal? If so, go to next step. If not, go to step 11 .
  6. Connect a test light between ground and the voltage supply circuit (Dark Green/White wire) at the shift lock solenoid. Does the test light illuminate? If so, go to next step. If not, go to step 15 .
  7. Test the shift lock solenoid ground circuit (Black wire) for an open or high resistance. Did you find and correct the condition? If so, go to step 20 . If not, go to step 12 .
  8. Turn the ignition switch to the OFF position. Disconnect the PNP switch harness connector. Connect a test light between ground and the ignition feed circuit (Pink wire) at the PNP switch. Turn the ignition switch to the ON position. Does the test light illuminate? If so, go to next step. If not, go to step 13 .
  9. Turn the ignition switch to the OFF position. Connect a 10-amp fused jumper between the ignition feed circuit (Pink wire) and the park signal circuit (Light Green wire) at the PNP switch. Connect a test light between ground and the stoplamp switch voltage supply circuit (Light Green/Black wire) at the BTSI fuse. Turn the ignition switch to the ON position. Does the test light illuminate? If so, go to next step. If not, go to step 16 .
  10. Inspect for proper PNP switch adjustment. See appropriate AUTOMATIC article in AUTOMATIC TRANSMISSIONS. Inspect the PNP switch for poor connections. Did you find and correct the condition? If so, go to step 20 . If not, go to step 17 .
  11. Inspect the stoplamp switch for poor connections. Did you find and correct the condition? If so, go to step 20 . If not, go to step 18 .
  12. Inspect the shift lock solenoid for poor connections. Did you find and correct the condition? If so, go to step 20 . If not, go to step 19 .
  13. Repair the open or short in the PNP switch ignition feed circuit (Pink wire). After repairs, go to step 20 .
  14. Repair the open or short in the stoplamp switch voltage supply circuit (Light Green/Black wire). After repairs, go to step 20 .
  15. Repair the open in the shift lock solenoid voltage supply circuit (Dark Green/White wire). After repairs, go to step 20 .
  16. Repair the open or short in the PNP switch park signal circuit (Light Green wire). After repairs, go to step 20 .
  17. Replace the PNP switch. See appropriate AUTOMATIC article in AUTOMATIC TRANSMISSIONS. After repairs, go to step 20 .
  18. Replace the stoplamp switch. See «STOPLAMP SWITCH»(ref-135819-S14984344712002022600000) under REMOVAL & INSTALLATION. After repairs, go to step 20 .
  19. Replace the shift lock solenoid. See «SHIFT LOCK SOLENOID (COLUMN SHIFT)»(ref-135819-S23940823032002022600000) under REMOVAL & INSTALLATION.
  20. Operate the system in order to verify the repair. Did you find and correct the condition? If so, system is okay. If not, go to step 2 .

TEST E: GEARSHIFT LEVER CAN BE MOVED WITHOUT BRAKE PEDAL DEPRESSED (FLOOR SHIFT)

Note. For circuit reference, see CONNECTOR IDENTIFICATION and WIRING DIAGRAMS .

  1. Did you review the DESCRIPTION and OPERATION and perform the necessary inspections? If so, go to next step. If not, see «DESCRIPTION & OPERATION»(ref-135819-S20023002132002022500000) .
  2. Apply the parking brake and block the wheels. Turn the ignition switch to the ON position. Attempt to move the gearshift lever out of the Park position. Does the gearshift lever move out of the Park position? If so, go to next step. If not, condition is intermittent. See «SYMPTOM DIAGNOSIS»(ref-135819-S02529281672002022500000) under TROUBLE SHOOTING.
  3. Place gearshift lever in the Park position. Turn the ignition switch to the OFF position. Press and hold the brake pedal. Attempt to move the gearshift lever out of the Park position. Does the gearshift lever move out of the Park position? If so, see «TEST A: PARK LOCK SOLENOID INOPERATIVE (FLOOR SHIFT)»(ref-135819-S16749215722002022500000) . If not, go to next step.
  4. Connect a test light between ground and the stoplamp switch voltage supply circuit (Light Green/Black wire). Does the test light illuminate? If so, go to next step. If not, go to step 10 .
  5. Connect a test light between ground and the stoplamp switch output circuit (Dark Green/White wire). Press and release the brake pedal several times. Does the test light turn ON and OFF with the brake pedal? If so, go to next step. If not, go to step 8 .
  6. Connect a test light between ground and the voltage supply circuit (Dark Green/White wire) at the shift lock solenoid. Does the test light illuminate? If so, go to next step. If not, go to step 11 .
  7. Test the shift lock solenoid ground circuit (Black wire) for an open or high resistance. Did you find and correct the condition? If so, go to step 14 . If not, go to step 9 .
  8. Inspect the stoplamp switch for poor connections. Did you find and correct the condition? If so, go to step 14 . If not, go to step 12 .
  9. Inspect the shift lock solenoid for poor connections. Did you find and correct the condition? If so, go to step 14 . If not, go to step 13 .
  10. Repair the open or short in the stoplamp switch voltage supply circuit (Light Green/Black wire). After repairs, go to step 14 .
  11. Repair the open in the shift lock solenoid voltage supply circuit (Dark Green/White wire). After repairs, go to step 14 .
  12. Replace the stoplamp switch. See «STOPLAMP SWITCH»(ref-135819-S14984344712002022600000) under REMOVAL & INSTALLATION. After repairs, go to step 14 .
  13. Replace the shift lock solenoid. See «FLOOR SHIFT CONTROL»(ref-135819-S29564780212002022600000) under REMOVAL & INSTALLATION.
  14. Operate the system in order to verify the repair. Did you find and correct the condition? If so, system is okay. If not, go to step 2 .

More articles — Shift Interlock Systems