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Test No. 2: Key Unlock Warning System Buzzer Does Not Sound

  1. Check AMI fuse (7.5-amp) and GAUGE fuse (7.5-amp). Fuses are located in fuse/relay box at driver's side of instrument panel. See Figure. If fuses are okay, go to next step. If any fuse is defective, repair short in wiring for appropriate fuse. See WIRING DIAGRAMS . For additional wiring for power supply circuit, see POWER DISTRIBUTION article in WIRING DIAGRAMS.
  2. Gain access to body ECU. Body ECU is located behind driver's side of instrument panel and contains 18-pin and 25-pin electrical connectors. See Figure. It may be necessary to remove instrument panel for access to body ECU. For servicing of instrument panel, see INSTRUMENT PANEL under REMOVAL & INSTALLATION in appropriate MANUAL A/C-HEATER SYSTEMS article.
  3. Turn ignition on. Using voltmeter, check voltage between body ground and IG terminal (Red/Black wire) at body ECU. See Fig 1. Voltage should be 9-14 volts. If voltage is not within specification, turn ignition off. Go to next step. If voltage is within specification, turn ignition off. Go to step  8.
  4. Check ignition relay. See IGNITION RELAY  under COMPONENT TESTS. If ignition relay is okay, go to next step. If ignition relay is defective, replace ignition relay and recheck operation of key unlock warning system buzzer.
  5. Check ignition switch. See IGNITION SWITCH  under COMPONENT TESTS. If ignition switch is okay, go to next step. If ignition switch is defective, replace ignition switch and recheck operation of key unlock warning system buzzer. See IGNITION SWITCH  under REMOVAL & INSTALLATION.
  6. Check wiring harness and electrical connectors between body ECU and ground connection. See WIRING DIAGRAMS . For body ECU electrical terminal identification, see Figure. 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 operation of key unlock warning system buzzer.
  7. Check wiring harness and electrical connectors between battery and body ECU. See WIRING DIAGRAMS . For additional power supply, see POWER DISTRIBUTION article in 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 and recheck operation of key unlock warning system buzzer.
  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 operation of key unlock warning system buzzer. See KEY UNLOCK WARNING SWITCH  under REMOVAL & INSTALLATION.
  9. Check wiring harness and electrical connectors between key unlock warning switch and body ECU. See WIRING DIAGRAMS in WARNING SYSTEMS article. Key unlock warning switch may also be referred to as unlock switch or unlock warning switch. For body ECU electrical terminal identification, see Figure. 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 operation of key unlock warning system buzzer.
  10. Check that retaining screw on door courtesy switch for each door is tight to provide good ground connection. Door courtesy switches are located on pillar post at rear of door. See Figure. If retaining screw for door courtesy switch is tight and good ground connection exists, go to next step. If retaining screw for door courtesy switch is loose, tighten retaining screw and recheck operation of key unlock warning system buzzer. If key unlock warning system buzzer still does not operate, go to next step. If key unlock warning system buzzer operates, the problem was the loose retaining screw on door courtesy switch.
  11. Check door courtesy switch for each door. See DOOR COURTESY SWITCH  under COMPONENT TESTS. If door courtesy switches are okay, go to next step. If any door courtesy switch is defective, replace door courtesy switch and recheck operation of key unlock warning system buzzer.
  12. Check wiring harness and electrical connectors between each door courtesy switch and body ECU. See WIRING DIAGRAMS in POWER DOOR LOCKS WITHOUT KEYLESS ENTRY - CARS 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 key unlock warning system buzzer.
  13. Check printed circuit board in combination meter on instrument cluster for problem which prevents operation of key unlock warning system buzzer. If printed circuit board is okay, go to next step. If printed circuit board is defective, repair or replace components and recheck operation of key unlock warning system buzzer.
  14. 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 operation of key unlock warning system buzzer.
  15. Replace body with a known-good body ECU and recheck operation of key unlock warning system buzzer. 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 and key unlock warning system buzzer for intermittent problem. Repair wiring harness or electrical connector as necessary.
    Fig 1: Checking Voltage At IG Terminal At Body Electronic Control Unit
    G00032745Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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