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Home >> Lexus >> 2004 >> GX 470 >> Repair and Diagnosis >> Suspension >> Electronic Suspension >> Electronic Modulated Suspension & Rear Air Suspension System - Diagnosis >> DTC C1776/76: Speed Sensor Circuit, DTC C1794/94 Right Front Speed Sensor Circuit, DTC C1795/95 Left Front Speed Sensor Circuit >> Inspection Procedure

Inspection Procedure

HINT:

Start the inspection from step 1 when using the hand-held tester, and start from step 2 when not using the hand-held tester.

  1. READ VALUE OF HAND-HELD TESTER 
    1. Connect the hand-held tester to DLC3.
    2. Turn the ignition switch ON, and push the hand-held tester main switch ON.
    3. Select the item "VEHICLE SPEED" in the DATA LIST, and read its value displayed on the hand-held tester.
    4. Check that there is no difference between the speed value output from the speed sensor displayed on the hand-held tester and the speed value displayed on the speedometer when driving the vehicle.

    Standard: There is almost no difference in the displayed speed values. 

    HINT:

    There is tolerance of +/- 10% in the speedometer indication.

    1. OK: CHECK AND REPLACE SUSPENSION CONTROL ECU (See  ELECTRONIC CIRCUIT INSPECTION PROCEDURE  ) 
    2. NG: GO TO NEXT STEP. 
  2. CHECK DIAGNOSTIC CODE OUTPUT 
    1. Check if the normal code is output by VSC.
    1. NG: REPAIR CIRCUIT INDICATED BY OUTPUT CODE 
    2. OK: GO TO NEXT STEP. 
  3. CHECK HARNESS AND CONNECTOR (SUSPENSION CONTROL ECU - SKID CONTROL ECU ASSY) 
    1. Check for open and short circuit in the harness and the connector between the suspension control ECU and the skid control ECU assy (See ELECTRONIC CIRCUIT INSPECTION PROCEDURE ).
    1. NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 
    2. OK: GO TO NEXT STEP. 
  4. INSPECT SKID CONTROL ECU ASSY (FLO OUTPUT, FRO OUTPUT) 
    1. Remove the skid control ECU with connector being connected.
    2. Turn the ignition switch ON.
    3. Connect an oscilloscope to between terminal S10-25 (FLO) and S9-8 (GND) and between terminal S10-24 (FRO) and S9-8 (GND) of the skid control ECU harness side connector.
      Fig 1: Connecting An Oscilloscope To Between Terminal S10-25 (FLO) And S9-8 (GND)
      G01421636Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    4. Drive the vehicle with about 20 km/h (12 mph), and check the signal waveform.

      Standard: Signal waveform appears as shown in the illustration. 

      Fig 2: Identifying Signal Waveform Appears In Illustration
      G01421637Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    HINT:

    As the engine speed becomes higher, the waveform cycle gets shorter.

    1. NG: CHECK AND REPLACE SKID CONTROL ECU ASSY (See  ELECTRONIC CIRCUIT INSPECTION PROCEDURE  ) 
    2. OK: GO TO NEXT STEP. 

      CHECK AND REPLACE SUSPENSION CONTROL ECU (See  ELECTRONIC CIRCUIT INSPECTION PROCEDURE  ) 

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