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Test No. 41: Buzzer Sounds But Keyless Entry System Will Not Operate

  1. Check multiplex control system to see if Diagnostic Trouble Code (DTC) B1242 (Toyota hand-held tester) or DTC No. 42 (DOOR open indicator light) exists. See MULTIPLEX CONTROL SYSTEMS - AVALON article. If DTC B1242 or DTC No. 42 does not exist, go to next step. If DTC B1242 or DTC No. 42 exists, perform service procedure for DTC and recheck keyless entry system operation.
  2. Ensure ignition is off. Disconnect electrical connector at door control receiver. See Figure. Note location of Body Electronic Control Unit (ECU) at driver's side of instrument panel on the fuse/relay box. See Figure. Disconnect electrical connector B4 at body ECU. Electrical connector B4 (25-pin) is located at each side of body ECU. See Figure.
  3. Using ohmmeter, check for continuity between terminal No. 3 (Green/Red wire) at electrical connector for door control receiver and terminal No. 7 (Green/Red wire) at electrical connector B4 (25-pin) for body ECU. For terminal identification on door control receiver electrical connector, see Figure. For terminal identification on electrical connector B4 for body ECU, see Figure. If continuity exists, reinstall electrical connectors and go to next step. If continuity does not exist, repair as necessary. Reinstall electrical connectors and recheck keyless entry system operation.
  4. Replace door control receiver with a known-good door control receiver and recheck keyless entry system operation. If keyless entry system still does not operate properly, go to next step. If keyless entry system operates properly, original door control receiver was defective.
  5. 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 or input signal does not exist, repair as necessary and recheck keyless entry system operation.
  6. Replace body ECU with a known-good body ECU and recheck keyless entry system operation. If keyless entry system operates properly, original body ECU was defective. If keyless entry system 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 KEYLESS ENTRY SYSTEMS - AVALON article. Repair wiring harness or electrical connector as necessary.
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