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Key Unlock Warning System Inoperative

WARNING: This page is about a different car, the 2000 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Perform this test when buzzer does not sound when driver's door is opened, ignition is in OFF position, and key is in ignition.

  1. Testing Power Source Circuits

    Perform steps  2- 4 under IGNITION SWITCH IS NOT SET TO EACH POSITION. Repair any problems found as necessary. If no problems were found, go to next step.

  2. Testing Key Unlock Warning Switch & Circuit

    Disconnect key unlock warning switch connector. See Figure. Using DVOM, check for continuity between switch connector terminal No. 1 (White/Black wire) and No. 2 (Red/Yellow wire). With key in ignition, continuity should be indicated. With key removed from ignition, continuity should not be indicated. If continuity is as specified, go to next step. If continuity is not as specified, replace key unlock warning switch.
  3. Disconnect body control ECU 25-pin connector B4. Check continuity in Red/Yellow wire between key unlock warning switch harness connector terminal No. 2 and body control ECU 25-pin connector B4, terminal No. 17. If continuity is not indicated, repair open in Red/Yellow wire as necessary and retest system. If continuity is indicated, go to next step.

  4. Testing Door Courtesy Switch & Circuit

    Check to see if door courtesy light comes on when each door is opened, and goes off when doors are closed. If courtesy light operates as specified, go to step  7. If courtesy light does not operate as specified, go to next step.
  5. Remove door courtesy switch for affected door. Using DVOM, check for continuity between switch terminal and switch body. With switch released, continuity should exist. With switch depressed, continuity should not exist. If continuity is not as specified, replace door courtesy switch and retest system. If continuity is as specified, go to next step.
  6. Check for open/short circuit in wiring between affected door courtesy switch and body ECU, and between door courtesy light and body ECU. See WIRING DIAGRAMS . Repair as necessary. If no problem was found, go to next step.

  7. Testing Multiplex Communications Circuits

    Check for open/short circuits between driver's door ECU and other modules on multiplex communication circuit. See MULTIPLEX CONTROL SYSTEMS - AVALON article. Repair any faulty circuits as necessary and retest system. If no problems were found, go to next step.

  8. Testing Driver's Door ECU

    Check all voltage inputs to driver's door ECU. See DRIVER'S DOOR ECU  under PIN VOLTAGE TESTS. If any voltage inputs are not as specified, repair affected circuit and retest system. See WIRING DIAGRAMS . If all voltage inputs are as specified, substitute known-good driver's door ECU and retest system. If system now works properly, replace driver's door ECU. If system still does not work, reinstall original driver's door ECU and go to next step.

  9. Testing Body Control ECU

    Check all voltage inputs to body control ECU. See BODY CONTROL ECU  under PIN VOLTAGE TESTS. If any voltage inputs are not as specified, repair affected circuit and retest system. See WIRING DIAGRAMS . If all voltage inputs are as specified, substitute known-good body control ECU and retest system. If system now works properly, replace body control ECU. If system still does not work, recheck all related system wiring and connections.


NOTE: Perform this test when buzzer sounds, and ignition is in ACC or ON positions.

  1. Testing Ignition Switch

    Disconnect 8-pin ignition switch harness connector on steering column. Using DVOM, check for continuity of ignition switch in all switch positions. See IGNITION SWITCH under COMPONENT TESTS in STEERING COLUMN SWITCHES - CARS article. If ignition switch continuity is not as specified, replace ignition switch. If ignition switch continuity is as specified, go to next step.

  2. Testing Power Source Circuits

    Perform steps  2- 4 under IGNITION SWITCH IS NOT SET TO EACH POSITION. Repair any problems found as necessary. If no problems were found, recheck all related system wiring and connections. See WIRING DIAGRAMS .
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