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

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   J108-3 (SPD) - J34-5 (+S)	Always	Below 1 Ω
   J108-3 (SPD) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Reconnect the combination meter assembly connector.
2. Check the output waveform.
   Fig 1: Identifying Radio Receiver Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   1. Connect an oscilloscope to terminal J108-3 (SPD) and body ground.
   2. Turn the engine switch on (IG).
   3. Turn a wheel slowly.
   4. Check the signal waveform according to the condition(s) in the table below.
      Fig 2: Identifying Waveform Graph

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Item	Condition
      Measurement terminal	J108-3 (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.

      TEXT IN ILLUSTRATION
      
      

      *1	Front view of wire harness connector (to Radio Receiver Assembly)

NG → See step   4 

OK → See step   3