LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2010 >> IS 250C Automatic >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Cruise Control Systems >> Dynamic Radar Cruise Control System (Diagnostic Codes & Circuit Tests) >> Dynamic Radar Cruise Control System >> Distance Control ECU Power Source Circuit >> Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Distance Control ECU Power Source Circuit: Procedure

  1. CHECK DISTANCE CONTROL ECU (B VOLTAGE) 
    1. Disconnect the distance control ECU connector.
      Fig 1: Identifying J17 Connector Terminals
      GTY262722Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Distance Control ECU)
    2. Turn the engine switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      J17-1 (B) - Body ground Engine switch on (IG) 11 to 14 V
    4. Reconnect the distance control ECU connector.

    NG → See step   3 

    OK: Go to next step 

  2. CHECK HARNESS AND CONNECTOR (DISTANCE CONTROL ECU - BODY GROUND) 
    1. Disconnect the distance control ECU connector.
    2. Measure the resistance according to the value(s) in the table below.
      Fig 2: Identifying J17 Connector Terminals
      GTY262719Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Distance Control ECU)

      Standard Resistance

      Tester Connection Condition Specified Condition
      J17-10 (SGND) - Body ground Always Below 1 Ω
      J17-12 (GND) - Body ground Always Below 1 Ω
    3. Reconnect the distance control ECU connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (DISTANCE CONTROL ECU - BODY GROUND) 

    OK → See step   9 

  3. INSPECT MAIN BODY ECU LH (LH-IG2 RELAY) 
    1. Disconnect the main body ECU LH connectors.
      Fig 3: Identifying Main Body ECU LH Connector Terminals
      GTY270755Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 Component without harness connected
      (Main Body ECU LH)      		 - -
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      LM-1 - LD-29 Battery voltage is not applied between terminals LD-13 and LD-8 10 kΩ or higher
      LM-1 - LD-29 Battery voltage applied between terminals LD-13 and LD-8 Below 1 Ω
    3. Reconnect the main body ECU LH connectors.

    NG → REPLACE MAIN BODY ECU LH (LH-IG2 RELAY) 

    OK: Go to next step 

  4. CHECK HARNESS AND CONNECTOR (DISTANCE CONTROL ECU - MAIN BODY ECU LH) 
    1. Disconnect main body ECU LH connector.
      Fig 4: Identifying J17 And LD Connector Terminals
      GTY276500Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Distance Control ECU)
      *2 Front view of wire harness connector
      (to Main Body ECU LH)
    2. Disconnect the distance control ECU connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      J17-1 (B) - LD-29 Always Below 1 Ω

      Standard Resistance (Check for short)

      Tester Connection Condition Specified Condition
      J17-1 (B) or LD-29 - Body ground Always 10 kΩ or higher
    4. Reconnect the main body ECU LH connector.
    5. Reconnect the distance control ECU connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (DISTANCE CONTROL ECU - MAIN BODY ECU LH) 

    OK: Go to next step 

  5. CHECK HARNESS AND CONNECTOR (LH-IG2 RELAY POWER SOURCE) 
    1. Disconnect main body ECU LH connector.
      Fig 5: Identifying LM Connector Terminals
      GTY262894Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Main Body ECU LH)
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      LM-1 - Body ground Always 11 to 14 V
    3. Reconnect the main body ECU LH connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (MAIN BODY ECU LH - BATTERY) 

    OK: Go to next step 

  6. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU LH - BODY GROUND) 
    1. Disconnect main body ECU LH connector.
      Fig 6: Identifying LD Connector Terminals
      GTY268089Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Main Body ECU LH)
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      LD-8 - Body ground Always Below 1 Ω
    3. Reconnect the main body ECU LH connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (MAIN BODY ECU LH - BODY GROUND) 

    OK: Go to next step 

  7. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU LH - POWER SOURCE CONTROL ECU) 
    1. Disconnect the main body ECU LH connector.
      Fig 7: Identifying J55 And LD Connector Terminals
      GTY285179Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Power Source Control ECU)
      *2 Front view of wire harness connector
      (to Main Body ECU LH)
    2. Disconnect the power source control ECU connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      LD-13 - J55-34 (IG1D) Always Below 1 Ω

      Standard Resistance (Check for Short)

      Tester Connection Condition Specified Condition
      LD-13 or J55-34 (IG1D) - Body ground Always 10 kΩ or higher
    4. Reconnect the main body ECU LH connector.
    5. Reconnect the power source control ECU connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (MAIN BODY ECU LH - POWER SOURCE CONTROL ECU) 

    OK → See step   8 

  8. GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING 
  9. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE 
scientia non olet · About LEMON Manuals