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Home >> Lexus >> 2009 >> LX 570 >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Communication Devices >> LEXUS Link System (Diagnostic Codes) >> LEXUS Link System >> DTC 4-7: EMERGENCY, VOL+ or VOL- Button has Connection Error >> Procedure
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DTC 4-7: EMERGENCY, VOL+ or VOL- Button has Connection Error: Procedure

  1. CHECK HARNESS AND CONNECTOR (TELEPHONE ECU ASSEMBLY - MAP LIGHT ASSEMBLY) 
    Fig 1: Identifying P3 ECU Connector Terminal And R7 Map Light Connector End View Terminal
    GTY116887Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Disconnect the P3 ECU connector.
    2. Disconnect the R7 map light connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      P3-5 (SIG1) - R7-30 (SIG1) Always Below 1 Ω
      P3-12 (SIG-) - R7-32 (GND3) Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR THEN CLEAR HISTORIC DTC 

    OK: Go to next step 

  2. INSPECT MAP LIGHT ASSEMBLY (MAYDAY SWITCH) 
    Fig 2: Identifying Map Light Assembly Connector Terminals (GND3 And SIG1)
    GTY116879Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Remove the map light. Refer to REMOVAL .
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      30 (SIG1) - 32 (GND3) Emergency button is pressed 305 to 313 Ω
      30 (SIG1) - 32 (GND3) VOL+ button is pressed 812 to 831 Ω
      30 (SIG1) - 32 (GND3) VOL- button is pressed 1811 to 1848 Ω

    NG → REPLACE MAP LIGHT ASSEMBLY (MAYDAY SWITCH) THEN CLEAR HISTORIC DTC 

    OK: Go to next step 

  3. REPLACE TELEPHONE ECU ASSEMBLY TOGETHER WITH MAYDAY BATTERY 

    NEXT → See step   4 

  4. PERFORM REGISTRATION. Refer to  REGISTRATION 
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