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Test No. 15: Lock Or Unlock Function Does Not Operate

  1. Note which door that lock and unlock function does not operate on. If lock and unlock function does not operate on driver's side front door, passenger's side front door or back (rear liftgate) door, go to next step. If lock and unlock function does not operate on driver's side rear door or passenger's side rear door, go to step  4.
  2. If Toyota hand-held tester is available, go to next step. If Toyota hand-held tester is not available, go to step  4.
  3. Connect hand-held tester to Data Link Connector (DLC) No. 3. See Figure. Using hand-held tester manufacturer's instructions, check operation of door unlock detection switch while using the DATA LIST. On driver's side front door and passenger's side front door, door unlock detection switch should be on when door lock knob is in the unlock position and should be off when door lock knob is in the lock position. On back (rear liftgate) door, door unlock detection switch should be on when door lock is in the unlock position and should be off when door lock is in the lock position. On all applications, if door unlock detection switch does not operate properly, remove hand-held tester. Go to next step. If door unlock detection switch operates properly, remove hand-held tester. Go to step  8.
  4. Check door unlock detection switch on the door in which the lock or unlock function does not operate. See DOOR UNLOCK DETECTION SWITCH  under COMPONENT TESTS. If door unlock detection switch is okay, go to next step. If door unlock detection switch is defective, replace door lock assembly and recheck operation of lock and unlock function.
  5. On driver's side front door, passenger's side front door or back (rear liftgate) door, go to next step. On driver's side rear door or passenger's side rear door, go to step  7.
  6. Check wiring harness and electrical connectors between door unlock detection switch and driver's door Electronic Control Unit (ECU) for driver's side front door, passenger's door ECU for passenger's side front door, or back door ECU for back (rear liftgate) door for the inoperative door lock. See WIRING DIAGRAMS in POWER DOOR LOCKS & REMOTE KEYLESS ENTRY SYSTEMS - SEQUOIA article. Driver's door ECU and passenger's door ECU are located on each door and is incorporated into the power window switch assembly. See Figure. Back door ECU is located on the back (rear liftgate) door and contains 2 electrical connectors. See Figure. If wiring harness and electrical connectors are okay, go to step  8. If wiring harness or electrical connector are defective, repair wiring harness or electrical connector as necessary and recheck operation of lock and unlock function.
  7. Check wiring harness and electrical connectors between door unlock detection switch and body Electronic Control Unit (ECU) for the appropriate inoperative door lock. See WIRING DIAGRAMS in POWER DOOR LOCKS & REMOTE KEYLESS ENTRY SYSTEMS - SEQUOIA article. Body ECU is located behind driver's side of instrument panel and contains 3 electrical connectors. See Figure. If wiring harness and electrical connectors are okay, go to step  10. If wiring harness or electrical connector are defective, repair wiring harness or electrical connector as necessary and recheck operation of lock and unlock function.
  8. Check for proper voltage and input signals for driver's door Electronic Control Unit (ECU) for driver's side front door, passenger's door ECU for passenger's side front door, or back door ECU for back (rear liftgate) door for the appropriate inoperative door lock. See DRIVER'S DOOR ELECTRONIC CONTROL UNIT , PASSENGER'S DOOR ELECTRONIC CONTROL UNIT  or BACK DOOR ELECTRONIC CONTROL UNIT  under PIN VOLTAGE TESTS. If proper voltage and input signals exist, go to next step. If proper voltage and input signals do not exist, repair as necessary and recheck operation of lock and unlock function.
  9. Replace appropriate door ECU with a known-good door ECU for the inoperative door lock and recheck operation of lock and unlock function. If lock and unlock function operates properly, original door ECU was defective. If lock and unlock function still does not operate properly, check wiring harness and electrical connectors for appropriate door ECU for intermittent problem. See WIRING DIAGRAMS in POWER DOOR LOCKS & REMOTE KEYLESS ENTRY SYSTEMS - SEQUOIA article. If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector are defective, repair as necessary and recheck operation of lock and unlock function.
  10. Check body Electronic Control Unit (ECU) for proper voltage and input signals. See BODY ELECTRONIC CONTROL UNIT  under PIN VOLTAGE TESTS. If proper voltage and input signals exist, go to next step. If proper voltage and input signals do not exist, repair as necessary and recheck operation of lock and unlock function.
  11. Replace body ECU with a known-good body ECU and recheck operation of lock and unlock function. If lock and unlock function operates properly, original body ECU was defective. If lock and unlock function still does not operate properly, check wiring harness and electrical connectors for body ECU and keyless entry system for an intermittent problem. See WIRING DIAGRAMS in POWER DOOR LOCKS & REMOTE KEYLESS ENTRY SYSTEMS - SEQUOIA article. Repair wiring harness or electrical connector as necessary.
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