Vehicle Speed Signal Circuit between Navigation Receiver Assembly and Combination Meter [08/2017 - 08/2019]: Procedure

1. Check the output waveform.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   1. Remove the combination meter assembly with the connector(s) still connected.
   2. Connect an oscilloscope to terminal H139-29 (+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	H139-29 (+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.

      TEXT IN ILLUSTRATION
      
      

      *a	Replacement Component with harness connected (Combination Meter Assembly)

Result: 

NG 

GO TO METER / GAUGE SYSTEM 

(Refer to HOW TO PROCEED WITH TROUBLESHOOTING [08/2015 - ] )

Result: 

OK 

See step  2

1. Disconnect the H158 navigation receiver assembly connector.
2. Disconnect the H139 combination meter assembly connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   H158-17 (SPD) - H139-29 (+S)	Always	Below 1 Ω
   H158-17 (SPD) - Body ground	Always	10 kΩ or higher

Result: 

OK 

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE 

(Refer to PROBLEM SYMPTOMS TABLE [08/2017 - 08/2019] )

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR