WIPER AND WASHER SYSTEM (w/ Rain Sensor) > 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


E177919E01


INSPECTION PROCEDURE

1.CHECK COMBINATION METER SYSTEM

  1. The circuit that sends vehicle speed signals to the combination meter system is inspected in the meter section (Click here).


NEXT


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


    E177920E01

  1. Disconnect the D41 windshield wiper relay assembly connector and D1 combination meter connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    D41-19 (SPD) - D1-16 (+S)
    		Always
    		Below 1 Ω
    D41-19 (SPD) or D1-16 (+S) - Body ground
    		Always
    		10 kΩ or higher

    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to Windshield Wiper Relay Assembly)
    *2
    		Front view of wire harness connector
    (to Combination Meter Assembly)



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


3.INSPECT COMBINATION METER (SPEED SENSOR SIGNAL)


    E177921E01

  1. Check the output waveform.

    1. Remove the combination meter assembly with the connector still connected (Click here).

    2. Connect an oscilloscope to terminal D1-16 (+S) and body ground.

    3. Turn the engine 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
      		Driving at approx. 20 km/h (12 mph)

      OK:
      The waveform is displayed as 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
Component with harness connected
(Combination Meter Assembly)


NG
REPLACE COMBINATION METER (Click here)
OK

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