METER / GAUGE SYSTEM Speedometer Malfunction

DESCRIPTION

The combination meter assembly receives vehicle speed signals from the brake booster with master cylinder assembly (skid control ECU) via the CAN communication line. The wheel speed sensors output voltages that vary according to the vehicle speed. The brake booster with master cylinder assembly (skid control ECU) supplies power to the wheel speed sensors. The brake booster with master cylinder assembly (skid control ECU) calculates the vehicle speed based on the pulses of the voltage.

Tech Tips


  • Factors that affect the indicated vehicle speed include the tire size, tire inflation, and tire wear. The speed indicated on the speedometer has an allowable margin of error. This can be tested using the GTS. For details about testing and the margin of error, see the reference chart.

    Click here

  • If the vehicle speed sensor circuit has a malfunction, the skid control ECU assembly stores DTCs. Troubleshoot the electronically controlled brake system.

    Click here

WIRING DIAGRAM

A01MFM4E21
*1 Brake Booster with Master Cylinder Assembly (Skid Control ECU)
*2 Combination Meter Assembly
*3 CAN Communication Line

CAUTION / NOTICE / HINT

Note


  • When replacing the combination meter assembly, make sure to replace it with a new one.

  • If the vehicle speed is outside the allowable range when tested, perform the operation check.

    Click here

Tech Tips

Before starting the following inspection, check the tire size and tire air pressure.

PROCEDURE


  1. CHECK FOR DTC (CAN COMMUNICATION SYSTEM)


    1. Check for DTCs.

      for LHD: Click here

      for RHD: Click here

      OK
      No DTCs are output.
      Result
      Result Proceed to
      OK A
      NG (for LHD) B
      NG (for RHD) C

    B

    GO TO CAN COMMUNICATION SYSTEM Click here

    C

    GO TO CAN COMMUNICATION SYSTEM Click here

    A

  2. CHECK FOR DTC (ELECTRONICALLY CONTROLLED BRAKE SYSTEM)


    1. Check for DTCs.

      Click here


      Chassis > ABS/VSC/TRC > Trouble Codes
      OK
      No DTCs are output.
      Result
      Proceed to
      OK
      NG

    NG

    GO TO ELECTRONICALLY CONTROLLED BRAKE SYSTEM Click here

    OK

  3. PERFORM ACTIVE TEST USING GTS (SPEED METER OPERATION)


    1. Using the GTS, perform the Active Test.

      Click here


      Body Electrical > Combination Meter > Active Test
      Tester Display Measurement Item Control Range Diagnostic Note
      Speed Meter Operation Speedometer

      • OFF, 0, 40, 80, 120, 160 (km/h) (for km/h)

      • OFF, 0, 40, 80, 120, 160 (mph) (for mph)

      There is a deviation in the values displayed on the speedometer display (Control range → Speedometer)


        with km/h units:

      • 40 → 42.0 to 46.0

      • 80 → 83.0 to 88.0

      • 120 → 125.0 to 132.0

      • 160 → 166.0 to 173.0


        with mph units (for RHD):

      • 40 → 42.0 to 44.0

      • 80 → 83.0 to 87.0

      • 120 → 125.0 to 129.0

      • 160 → 166.0 to 171.0

      Body Electrical > Combination Meter > Active Test
      Tester Display
      Speed Meter Operation
      OK
      Speedometer indication is normal.
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE COMBINATION METER ASSEMBLY Click here

    OK

  4. READ VALUE USING GTS (VEHICLE SPEED METER)


    1. Using the GTS, read the Data List.

      Click here


      Body Electrical > Combination Meter > Data List
      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Vehicle Speed Meter Vehicle speed Min.: 0 km/h (0 mph), Max.: 255 km/h (158 mph) Almost the same as the actual vehicle speed -

      Body Electrical > Combination Meter > Data List
      Tester Display
      Vehicle Speed Meter

      Tech Tips


      • When the Data List values of the ECUs match, an internal malfunction of the combination meter assembly is suspected.

      • When the Data List values of the ECUs do not match, a signal output error of the brake booster with master cylinder assembly (skid control ECU) or an internal malfunction of the combination meter assembly is suspected.

      OK
      Vehicle speed displayed on the GTS is almost the same as the actual vehicle speed measured using a speedometer tester (calibrated chassis dynamometer).
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

  5. READ VALUE USING GTS (VEHICLE SPEED)


    1. Using the GTS, read the Data List.

      Click here


      Chassis > ABS/VSC/TRAC > Data List
      Tester Display Measurement Item Normal Condition Reference Value Diagnostic Note
      Vehicle Speed Vehicle speed Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph) Almost the same as the actual vehicle speed -

      Chassis > ABS/VSC/TRAC > Data List
      Tester Display
      Vehicle Speed
      OK
      Vehicle speed displayed on the GTS is almost the same as the actual vehicle speed measured using a speedometer tester (calibrated chassis dynamometer).
      Result
      Result Proceed to
      OK A
      NG (for LHD) B
      NG (for RHD) C

    B

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU) Click here

    C

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU) Click here

    A

  6. CHECK COMBINATION METER ASSEMBLY


    1. Replace the combination meter assembly.

      Click here

    2. Check that the operation of the speedometer returns to normal.

      OK
      The operation of the speedometer returns to normal.
      Result
      Result Proceed to
      OK A
      NG (for LHD) B
      NG (for RHD) C

    A

    END (COMBINATION METER ASSEMBLY IS DEFECTIVE)

    B

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU) Click here

    C

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU) Click here