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 G16-6 (+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 | |
Measurement terminal |
G16-6 (+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. 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. |
 |
|
*a | Component with harness connected
(Combination Meter Assembly) | | |
| NG |
 | GO TO METER / GAUGE SYSTEM |
|
OK |
 | |
| 2. |
INSPECT STEREO COMPONENT AMPLIFIER ASSEMBLY (INPUT WAVEFORM) |
(a) Check the input waveform.
|
*a | Component with harness connected
(Stereo Component Amplifier Assembly) |
- | - |
(1) Remove the stereo component amplifier assembly with the connector(s) still connected.
(2) Connect an oscilloscope to terminal G8-11 (SPD) 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 | |
Measurement terminal |
G8-11 (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.
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 |
| NG |
| REPAIR OR REPLACE HARNESS OR CONNECTOR | | 
