WIPER AND WASHER SYSTEM Speed Signal Circuit

DESCRIPTION

The windshield wiper relay assembly receives a vehicle speed signal from the combination meter assembly 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 following diagram will not operate normally.

WIRING DIAGRAM


  1. A013ARXE01

PROCEDURE


  1. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)


    1. A0139SKC02
      *a

      Component with harness connected

      (Combination Meter Assembly)

      Check the output waveform.


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

      2. Connect an oscilloscope to terminal E46-6 (+S) and body ground.

      3. Turn the power switch on (IG).

      4. 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 displayed as shown in the illustration.

        Tech Tips

        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
      Result
      OK
      NG

    NG

    GO TO METER / GAUGE SYSTEM Click here

    OK

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


    1. Disconnect the E95 windshield wiper relay assembly connector.

    2. Disconnect the E46 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E95-24 (SPD) - E46-6 (+S) Always Below 1 Ω
      Result
      Result
      OK
      NG

    OK

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

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR