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Home › Lexus › 2008 › LX 570 › Repair and Diagnosis › Suspension › Suspension Control Systems › Suspension Control › Active Height Control Suspension › DTC C1791 Absorber Control Switch Circuit (Test Mode DTC) › Inspection Procedure

Inspection Procedure

NOTE:
  • Before performing troubleshooting, inspect the connectors of related circuits.
  • If the suspension control ECU or height control sensor is replaced, the vehicle height offset calibration must be performed (See INITIALIZATION ).
  1. READ VALUE USING TECHSTREAM (SPORT SWITCH, COMFORT SWITCH) 
    1. Turn the engine switch off.
    2. Connect the Techstream to the DLC3.
    3. Turn the engine switch on (IG) and the Techstream on.
    4. Enter the following menus: Chassis / AHC / Data List.
    5. According to the display on the Techstream, read the Data List.

    AHC 

    AHC REFERENCE

    Tester Display Measurement Item/Range Normal Condition Diagnostic Note
    SPORT Switch Damping mode select switch (SPORT) /
    ON or OFF    		 ON: SPORT
    OFF: NORMAL or COMFORT    		 -
    COMFORT Switch Damping mode select switch (COMFORT) /
    ON or OFF    		 ON: COMFORT
    OFF: NORMAL or SPORT    		 -

    OK: On the Techstream screen, item changes between ON and OFF according to switch operation. 

    NG:  Go to step  3

    OK: Go to next Step 

  2. TEST MODE INSPECTION 
    1. Refer to the Test Mode Procedure and perform the signal check. Check that test mode DTC C1791 is cleared (See TEST MODE PROCEDURE ).

    Result 

    RESULT REFERENCE

    Result Proceed to
    DTC C1791 is not cleared A
    DTC C1791 is cleared B

    B: USE SIMULATION METHOD TO CHECK  (See HOW TO PROCEED WITH TROUBLESHOOTING )

    A: REPLACE SUSPENSION CONTROL ECU  (See REMOVAL )

  3. INSPECT INTEGRATION CONTROL AND PANEL (DAMPING MODE SELECT SWITCH) 
    1. Remove the integration control and panel (See REMOVAL ).
    2. Measure the resistance according to the value (s) in the table below.

    Standard Resistance 

    STANDARD RESISTANCE

    Tester Connection Switch Condition Specified Condition
    3 (ECU1) - 6 (E) SPORT Below 1 Ω
    Except SPORT 10 kΩ or higher
    5 (ECU2) - 6 (E) COMF Below 1 Ω
    Except COMF 10 kΩ or higher

    NG: REPLACE INTEGRATION CONTROL AND PANEL  (See REMOVAL )

    Fig 1: Identifying Integration Control And Panel Connector Terminals
    G05761339Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to next Step 

  4. CHECK HARNESS AND CONNECTOR (SUSPENSION CONTROL ECU - SWITCH AND BODY GROUND) 
    Fig 2: Identifying K30 ECU Connector And Integration Control And Panel Connector
    G05761340Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Disconnect the K30 ECU connector.
    2. Disconnect the V4 integration control and panel connector.
    3. Measure the resistance according to the value (s) in the table below.

    Standard Resistance 

    STANDARD RESISTANCE

    Tester Connection Condition Specified Condition
    K30-2 (TSW1) - V4-3 (ECU1) Always Below 1 Ω
    K30-2 (TSW1) - Body ground Always 10 kΩ or higher
    K30-9 (TSW2) - V4-5 (ECU2) Always Below 1 Ω
    K30-9 (TSW2) - Body ground Always 10 kΩ or higher
    V4-6 (E) - Body ground Always Below 1 Ω

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: REPLACE SUSPENSION CONTROL ECU  (See REMOVAL )

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