RX400h · Service Manual BODY ELECTRICAL

Vehicle Speed Signal Circuit between Stereo Component Amplifier and Combination Meter

Circuit diagnosis

DESCRIPTION

This circuit is necessary for the ASL (Auto Sound Leveliser) built into the stereo component amplifier. Speed signals are received from the combination meter and used for the ASL.
The ASL function automatically adjusts the sound data in order to enable hearing the clear audio sound even when vehicle noise increases (as vehicle noise increases, the volume is turned up etc.). Standard System: Speed signals and a microphone for the ASL built into the stereo component amplifier are used.
Mark Levinson System: Speed signals are used.

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 an ECU, all systems in the diagram below will not operate normally.


WIRING DIAGRAM

E110887E03
E110887E04

INSPECTION PROCEDURE


1. CHECK OPERATION OF SPEEDOMETER

  1. Drive the vehicle and check if the function of the speedometer on the combination meter is normal.

    OK:
    Actual vehicle speed and the speed indicated on the speedometer are the same.

    HINT:
    The vehicle speed sensor is functioning normally when the indication on the speedometer is normal.



 NG
CHECK COMBINATION METER
OK


2. INSPECT STEREO COMPONENT AMPLIFIER

  1. E110888E04
    Standard System:Disconnect the stereo component amplifier connector S27.

  1. Mark Levinson System:Disconnect the stereo component amplifier connector S28.

  1. Measure voltage.

    1. Jack up either one of the drive wheels.

    2. Move the shift lever to the neutral position.

    3. Turn the ignition switch to the ON position.

    4. E110855E01
      Measure the voltage between terminal SPD of the stereo component amplifier and body ground when the drive wheels are turned slowly.

      OK:
      Voltage pulses as shown in the illustration.



 NG
Go to step 4
OK


3. CHECK SYSTEM TYPE

  1. Choose type to be inspected.


Result:
Type
 Proceed to
Standard System
 A
Mark Levinson System
 B



B
REPLACE STEREO COMPONENT AMPLIFIER (MARK LEVINSON SYSTEM)
A

REPLACE STEREO COMPONENT AMPLIFIER (STANDARD SYSTEM)

4. CHECK HARNESS AND CONNECTOR (COMBINATION METER - STEREO COMPONENT AMPLIFIER)

  1. E111999E02
    Standard System:Disconnect the stereo component amplifier connector S27 and combination meter connector C8.

  1. Mark Levinson System:Disconnect the stereo component amplifier connector S28 and combination meter connector C8.

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

    Standard resistance:
    Tester connection
    		 Condition
    		 Specified condition
    SPD - C8-6
    		 Ignition switch OFF
    		 Below 1 Ω



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


5. CHECK HARNESS AND CONNECTOR (COMBINATION METER - STEREO COMPONENT AMPLIFIER)

  1. E112075E02
    Standard System:Disconnect the stereo component amplifier connector S27 and combination meter connector C8.

  1. Mark Levinson System:Disconnect the stereo component amplifier connector S28 and combination meter connector C8.

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

    Standard resistance:
    Tester connection
    		 Condition
    		 Specified condition
    SPD - Body ground
    		 Ignition switch OFF
    		 10 kΩ or higher

    HINT:
    If the resistance between terminal SPD and body ground is less than 10 kΩ, there may be a short in a wire harness, connector, or ECU.



 NG
REPAIR OR REPLACE HARNESS OR CONNECTOR OR CHECK EACH ECU
OK

REPLACE COMBINATION METER


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