Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter: Procedure

1. Check the output waveform.
   Fig 1: Inspecting Combination Meter Assembly (Output Waveform)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   1. Remove the combination meter assembly with the connector still connected.
   2. Connect an oscilloscope to terminal E55-36 (+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
      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	Component with harness connected (Combination Meter Assembly)

NG → See step   4 

OK: Go to next step 

1. Disconnect the radio receiver assembly connector and the combination meter assembly connector.
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   E32-3 (SPD) - E55-36 (+S)	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (RADIO RECEIVER ASSEMBLY - JUNCTION CONNECTOR) 

OK → See step   3