Lexus ES: Vehicle Speed Signal Circuit between Stereo Component Amplifier and Combination Meter
DESCRIPTION
The stereo component amplifier assembly receives a vehicle speed signal from the combination meter assembly to control the ASL function.
HINT:
- A voltage of 12 V or 5 V is output from each ECU 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 its respective systems based on this 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
PROCEDURE
| 1. | INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM) |
| (a) Check the output waveform. (1) Remove the combination meter assembly with the connector(s) still connected. (2) Connect an oscilloscope to terminal G17-19 (+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.
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. |
|
| NG |  | GO TO METER / GAUGE SYSTEM |
|
| 2. | INSPECT STEREO COMPONENT AMPLIFIER ASSEMBLY (INPUT WAVEFORM) |
| (a) Check the input waveform. (1) Remove the stereo component amplifier assembly with the connector(s) still connected. (2) Connect an oscilloscope to terminal G11-17 (SPD) 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.
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. |
|
| OK | | PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE |
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| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY - COMBINATION METER ASSEMBLY) |
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CAUTION / NOTICE / HINT NOTICE:
Depending on the parts that are replaced during vehicle inspection or maintenance, performing initialization, registration or calibration may be needed. Refer to Pre
SEE MORE:
Lack of Power
DESCRIPTION Problem Symptom Suspected Area Trouble Area
Engine speed fluctuation due to abnormal combustion
Idle speed too low or high
Strong engine vibration due to above symptoms
Ignition malfunction
Deviation in air fuel ratio (Excessive or insufficient intake air volume
Initialization
INITIALIZATION CHANGE GRILLE SHUTTER CONTROL MODE AND/OR PERFORM INITIALIZATION (a) In the following situations, it is necessary to change the grille shutter control mode and/or initialize the grille shutter system. Change Control Mode (Normal Mode → Maintenance Mode) Change Control Mo
