Vehicle Speed Signal Circuit between Stereo Component Amplifier and Combination Meter [11/2018 - 10/2022]: Procedure

1. Check the output waveform.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Component with harness connected (Combination Meter Assembly)

   1. Remove the combination meter assembly with the connector(s) still connected.

      Refer to REMOVAL [11/2018 - 10/2022]

   2. Connect an oscilloscope to terminal G18-36 (+S) and body ground.
   3. Turn the ignition switch to ON.
   4. Turn a wheel slowly.
   5. Check the signal waveform according to the condition(s) in the table below.

      Item	Condition
      Measurement terminal	G18-36 (+S) - Body ground
      Tool setting	5 V/DIV., 20 ms./DIV.
      Vehicle condition	Wheel being rotated

      OK

      The waveform is similar to that shown in the illustration.

      HINT: 

      When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

GO TO METER / GAUGE SYSTEM. Refer to  Speed Signal Circuit [11/2018 - 10/2019]  , or refer to  Speed Signal Circuit [10/2019 - 08/2020]  , or refer to  Speed Signal Circuit [08/2020 - 12/2021]  , or refer to  Speed Signal Circuit [12/2021 - 10/2022] 

Result: 

OK 

See step  2

1. Check the input waveform.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a

   Component with harness connected (Stereo Component Amplifier Assembly)

   -

   -

   1. Remove the stereo component amplifier assembly with the connector(s) still connected.

      Refer to REMOVAL [11/2018 - 10/2022]

   2. Connect an oscilloscope to terminal M3-11 (SPD) and body ground.
   3. Turn the ignition switch to ON.
   4. Turn a wheel slowly.
   5. Check the signal waveform according to the condition(s) in the table below.

      Item	Condition
      Measurement terminal	M3-11 (SPD) - Body ground
      Tool setting	5 V/DIV., 20 ms./DIV.
      Vehicle condition	Wheel being rotated

      OK

      The waveform is similar to that shown in the illustration.

      HINT: 

      When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [11/2018 - 02/2019]  , or refer to  PROBLEM SYMPTOMS TABLE [02/2019 - 10/2019]  , or refer to  PROBLEM SYMPTOMS TABLE [10/2019 - 10/2022] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR