Toyota Camry (XV70): 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
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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 K21-6 (+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.
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. |
|
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| NG | .gif) | GO TO METER / GAUGE SYSTEM
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| 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 K10-11 (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 |
K10-11 (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 |
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