Vehicle Speed Signal Circuit between Stereo Component Amplifier and Combination Meter [11/2017 - ]: 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.
   2. Connect an oscilloscope to terminal O3-19 (+S) and body ground.
   3. Turn the engine switch on (IG).
   4. Turn a wheel slowly.
   5. Check the signal waveform according to the condition(s) in the table below.

      Item	Condition
      Measurement terminal	O3-19 (+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 [11/2017 - 09/2020]  , or refer to  Speed Signal Circuit [09/2020 - ] 

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.
   2. Connect an oscilloscope to terminal T20-17 (SPD) and body ground.
   3. Turn the engine switch on (IG).
   4. Turn a wheel slowly.
   5. Check the signal waveform according to the condition(s) in the table below.

      Item	Condition
      Measurement terminal	T20-17 (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 [11/2017 - 03/2019]  , or refer to  PROBLEM SYMPTOMS TABLE [03/2019 - 09/2020]  , or refer to  PROBLEM SYMPTOMS TABLE [09/2020 - 01/2023]  , or refer to  PROBLEM SYMPTOMS TABLE [01/2023 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR