LIGHTING SYSTEM > Speed Signal Circuit

for Preparation Click here


DESCRIPTION

The headlight leveling ECU assembly receives the vehicle speed signal from the combination meter assembly.

HINT:
  1. A voltage of 12 V or 5 V is output from each ECU and then input to the combination meter. The signal is changed to a pulse signal at the transistor in the combination meter. Each ECU controls the respective system based on the pulse signal.
  2. 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.CHECK COMBINATION METER SYSTEM

  1. The circuits that send vehicle speed signals to this system are inspected in the meter section (Click here).

  1. During inspection for the meter system, if there is an instruction that indicates to go back to inspections for the lighting system, proceed to the next step.


NEXT


2.CHECK HARNESS AND CONNECTOR (HEADLIGHT LEVELING ECU ASSEMBLY - COMBINATION METER ASSEMBLY)

  1. Disconnect the H19 combination meter assembly connector.

  1. Disconnect the A46 headlight leveling ECU assembly connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    A46-16 (SPDR) - H19-40 (+S)
    		Always
    		Below 1 Ω



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


3.INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)


    E159354E68

  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. 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.

      Text in Illustration 
      *a
      		Component with harness connected
      (Combination Meter Assembly)

      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.



NG
REPLACE COMBINATION METER ASSEMBLY (Click here)
OK

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