WIPER AND WASHER SYSTEM > Speed Signal Circuit

for Preparation Click here


DESCRIPTION

The windshield wiper relay assembly receives a vehicle speed signal from the combination meter to control the automatic windshield wiper system.
A voltage of 12 V or 5 V is output from the combination meter assembly and then input to the skid control ECU.
A voltage of 12 V or 5 V is output from each ECU or relay and then input to the combination meter assembly.
The signal is changed to a pulse signal at the transistor in the combination meter assembly.
Each ECU controls the respective system based on the pulse signal.
If a short occurs in any of the ECUs or in the wire harness connected to an ECU, all systems in the diagram below will not operate normally.

WIRING DIAGRAM


E217460E01


INSPECTION PROCEDURE

1.INSPECT COMBINATION METER ASSEMBLY (SPEED SENSOR SIGNAL)


    E165890E11

  1. Check the output waveform.

    1. Remove the combination meter assembly with the connector still connected.

    2. Connect an oscilloscope to terminal H19-40 (+S) and body ground.

    3. Turn the power switch on (IG).

    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
GO TO METER / GAUGE SYSTEM (Click here)
OK


2.CHECK HARNESS AND CONNECTOR (WINDSHIELD WIPER RELAY ASSEMBLY - COMBINATION METER)

  1. Disconnect the H75 windshield wiper relay assembly connector and H19 combination meter assembly connector.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    H75-19 (SPD) - H19-40 (+S)
    		Always
    		Below 1 Ω



NG
Go to step 3
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE (Click here)  

3.CHECK HARNESS AND CONNECTOR (WINDSHIELD WIPER RELAY ASSEMBLY - JUNCTION CONNECTOR)

  1. Disconnect the H75 windshield wiper relay assembly connector and H117 junction connector.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    H75-19 (SPD) - H117-19
    		Always
    		Below 1 Ω



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

GO TO METER / GAUGE SYSTEM (Click here)