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Test No. 2: Key Unlock Warning System Buzzer Inoperative

NOTE: Test should be performed if key unlock warning system buzzer does not sound when driver's side front door is opened with ignition off and ignition key in ignition lock cylinder.
  1. Power source for Body Electronic Control Unit (ECU) should be checked. Body ECU may also be referred to as integration relay. Check the following fuses: DOOR (25-amp), GAUGE (10-amp) and POWER (30-amp). These fuses are located in the fuse/relay box at driver's side of instrument panel. See Figure. Also, check DOME fuse (10-amp). DOME fuse is located in fuse/relay box at driver's side front corner of engine compartment. See Figure. If all fuses are okay, go to next step. If any fuse is defective, replace fuse and repair wiring harness or electrical connector on wiring circuit as necessary. See WIRING DIAGRAMS . For additional wiring for power supply circuit, see POWER DISTRIBUTION article in WIRING DIAGRAMS.
  2. Check power relay. See POWER RELAY  under COMPONENT TESTS. If power relay is okay, go to next step. If power relay is defective, replace power relay and recheck key unlock warning system buzzer operation.
  3. Note location of body ECU at driver's side of instrument panel on the fuse/relay box. See Figure. Body ECU may also be referred to as integration relay. Electrical connector I13 (7-pin or 25-pin) and electrical connector I16 (18-pin) are located at body ECU and a 12-pin electrical connector is located at rear of body ECU. See Figure.
  4. Turn ignition on. Using voltmeter, check voltage between terminal No. 7 (IG terminal) and ground circuit at terminal No. 10 ("E" terminal) at body ECU 12-pin electrical connector. See Figure. Voltage should be 10-14 volts. Go to next step.
  5. Turn ignition off. Disconnect electrical connectors at body ECU. Using voltmeter, check voltage between terminal No. 1 ("B" terminal) and ground circuit at terminal No. 10 ("E" terminal) at body ECU 12-pin electrical connector. See Figure. Voltage should be 10-14 volts. On models with power door locks, using voltmeter, check voltage between ground circuit at terminal No. 10 ("E" terminal) at body ECU 12-pin electrical connector and terminals No. 15 (Blue/White wire) and No. 24 (Black/Red wire) at body ECU electrical connector I13. See Figure. Voltage should be 10-14 volts.
  6. On all models, if all voltage readings are within specification, reinstall electrical connectors and go to step  8. If any voltage is not within specification, check for open in wiring harness and electrical connectors between ground connection and terminal No. 10 at body ECU 12-pin electrical connector. See WIRING DIAGRAMS . If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
  7. Check wiring harness and electrical connectors between battery, ignition switch and body ECU. See WIRING DIAGRAMS . For additional wiring for power supply circuit, see POWER DISTRIBUTION article in WIRING DIAGRAMS. Repair wiring harness or electrical connector as necessary.
  8. Check key unlock warning switch. See KEY UNLOCK WARNING SWITCH  under COMPONENT TESTS. If key unlock warning switch is okay, go to next step. If key unlock warning switch is defective, replace key unlock warning switch and recheck key unlock warning system buzzer operation. See KEY UNLOCK WARNING SWITCH  under REMOVAL & INSTALLATION.
  9. Check key unlock warning switch circuit by checking Blue/Black wire and electrical connectors between terminal No. 1 at key unlock warning switch and terminal No. 5 at body ECU 12-pin electrical connector. See Figure. See WIRING DIAGRAMS in KEYLESS ENTRY SYSTEMS - SIENNA article or POWER DOOR LOCKS - TRUCKS (EXCEPT SEQUOIA) article. Key unlock warning switch may also be referred to as unlock switch or unlock warning switch. Body ECU may also be referred to as integration relay. If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary and recheck key unlock warning system buzzer operation.
  10. Open each door and check that door courtesy light comes on when door is opened and goes off when door is closed. If any door courtesy light does not operate properly when door is open and closed, go to next step. If door courtesy light operates properly when each door is open and closed, go to step  13.
  11. Check door courtesy switch. See DOOR COURTESY SWITCH  under COMPONENT TESTS. If door courtesy switch is okay, go to next step. If door courtesy switch is defective, replace door courtesy switch and recheck key unlock warning system buzzer operation.
  12. Check wiring harness and electrical connectors between door courtesy switch and body ECU, and between door courtesy light and body ECU. See WIRING DIAGRAMS in KEYLESS ENTRY SYSTEMS - SIENNA article or POWER DOOR LOCKS - TRUCKS (EXCEPT SEQUOIA) article. If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary and recheck key unlock warning system buzzer operation.
  13. Check body 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 key unlock warning system buzzer operation.
  14. Replace body ECU with a known-good body ECU and recheck key unlock warning system buzzer operation. If key unlock warning system buzzer operates properly, original body ECU was defective. If key unlock warning system buzzer still does not operate properly, check wiring harness and electrical connectors for body ECU for an intermittent problem. See WIRING DIAGRAMS in KEYLESS ENTRY SYSTEMS - SIENNA article or POWER DOOR LOCKS - TRUCKS (EXCEPT SEQUOIA) article. Repair wiring harness or electrical connector as necessary.
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