DESCRIPTION
The stereo component amplifier assembly receives a vehicle speed signal from the combination meter assembly to control the ASL function.
Tech Tips
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 the respective systems 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
INSPECTION PROCEDURE
PROCEDURE
INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)
*a | Component with harness connected (Combination Meter Assembly) |
Check the output waveform.
Remove the combination meter assembly with the connector(s) still connected.
Connect an oscilloscope to terminal I18-9 (+S) and body ground.
Turn the power switch on (IG).
Turn a wheel slowly.
Check the signal waveform according to the condition(s) in the table below.
Item | Condition |
---|---|
Measurement terminal | I18-9 (+S) - Body ground |
Tool setting | 5 V/DIV., 20 ms./DIV. |
Vehicle condition | Wheel being rotated |
OK |
---|
The waveform is similar to that 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.
NG |
GO TO METER / GAUGE SYSTEM Click here |
OK |
INSPECT STEREO COMPONENT AMPLIFIER ASSEMBLY (INPUT WAVEFORM)
*a | Component with harness connected (Stereo Component Amplifier Assembly) |
Check the input waveform.
Remove the stereo component amplifier assembly with the connector(s) still connected.
Connect an oscilloscope to terminal I69-11 (SPD) and body ground.
Turn the power switch on (IG).
Turn a wheel slowly.
Check the signal waveform according to the condition(s) in the table below.
Item | Condition |
---|---|
Measurement terminal | I69-11 (SPD) - Body ground |
Tool setting | 5 V/DIV., 20 ms./DIV. |
Vehicle condition | Wheel being rotated |
OK |
---|
The waveform is similar to that 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.
NG |
CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY - COMBINATION METER ASSEMBLY) Click here |
OK |
PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here
CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY - COMBINATION METER ASSEMBLY)
Disconnect the stereo component amplifier assembly connector.
Disconnect the combination meter assembly connector.
Measure the resistance according to the value(s) in the table below.
Standard Resistance | ||||||
---|---|---|---|---|---|---|
|
NG |
CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY - JUNCTION CONNECTOR) Click here |
OK |
PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here
CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY - JUNCTION CONNECTOR)
Disconnect the stereo component amplifier assembly connector.
Disconnect the junction connector.
Measure the resistance according to the value(s) in the table below.
Standard Resistance | ||||||
---|---|---|---|---|---|---|
|
NG |
REPAIR OR REPLACE HARNESS OR CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY - JUNCTION CONNECTOR) |
OK |
REPAIR OR REPLACE HARNESS OR CONNECTOR (JUNCTION CONNECTOR)