LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2009 >> GS 350 AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 78 (Smart Key System (Keyless Entry) (Diagnostics - Introduction)) >> Smart Key System >> Diagnosis System >> Diagnosis System
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnosis System

WARNING: This page is about a different car, the 2011 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.
  1. DESCRIPTION 
    1. The certification ECU controls the function of the smart key system on the vehicle. Data of the smart key system and the Diagnostic Trouble Code (DTC) can be read in the Data Link Connector 3 (DLC3) of the vehicle. When a malfunction occurs in the smart key system, even though the smart key system warning light does not turn on, DTCs can be checked.

      When the system seems to be malfunctioning, use Techstream to check for a malfunction and perform repairs.

  2. CHECK DLC3 
    1. The vehicle's ECU uses ISO 15765-4 for communication protocol. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 15765-4 format.
      Fig 1: Identifying DLC3 Connector Terminal Identification
      GTY103674Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      Symbols (Terminal No.) Terminal Description Condition Specified Condition
      SIL (7) - SG (5) Bus "+" line During transmission Pulse generation
      CG (4) - Body ground Chassis ground Always Below 1 Ω
      SG (5) - Body ground Signal ground Always Below 1 Ω
      BAT (16) - Body ground Battery positive Always 10 to 14 V
      CANH (6) - CANL (14) CAN bus line Engine switch off* 54 to 69 Ω
      CANH (6) - CG (4) HIGH-level CAN bus line Engine switch off* 200 Ω or higher
      CANL (14) - CG (4) LOW-level CAN bus line Engine switch off* 200 Ω or higher
      CANH (6) - BAT (16) HIGH-level CAN bus line Engine switch off* 6 kΩ or higher
      CANL (14) - BAT (16) LOW-level CAN bus line Engine switch off* 6 kΩ or higher
      NOTE:

      *: Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the engine switch, any other switches or the doors.

      If the result is not as specified, the DLC3 may have a malfunction. Repair or replace the harness and connector.

    2. Connect the cable of Techstream to the DLC3, turn the engine switch on (IG) and attempt to use Techstream. If the screen displays a communication error message, a problem exists in the vehicle side or tester side.

      HINT: 

      • If communication is normal when the tool is connected to another vehicle, inspect the DLC3 on the original vehicle.
      • If communication is still impossible when the tool is connected to another vehicle, the problem is probably in the tool itself. Consult the Service Department listed in the tool's instruction manual.