| Last Modified: 11-29-2007 | 1.6 J | |
| Service Category: Audio/Visual/Telematics | Section: Audio/Video | |
| Model Year: 2008 | Model: Sequoia | Doc ID: RM0000014OU01OX |
| Title: AUDIO / VIDEO: AUDIO AND VISUAL SYSTEM: DESCRIPTION (2008 Sequoia) | ||
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Vehicle Speed Signal Circuit between Stereo Component Amplifier and Combination Meter |
DESCRIPTION
This circuit is necessary for the ASL (Auto Sound Leveliser) built into the stereo component amplifier assembly. Speed signals are received from the combination meter assembly and used for the ASL.
The ASL function automatically adjusts the sound data in order to enable the driver to hear clear audio sound even when vehicle noise increases (as vehicle noise increases, the volume is turned up, etc.).
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 the respective system based on the pulse signal.
- If a short occurs in an ECU, all systems in the diagram below will not operate normally.
WIRING DIAGRAM
INSPECTION PROCEDURE
PROCEDURE
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1. |
CHECK OPERATION OF SPEEDOMETER |
(a) Drive the vehicle and check if the function of the speedometer on the combination meter assembly 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.
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The speed indicated on the speedometer has an allowable margin of error. This can be tested using a speedometer tester (calibrated chassis dynamometer). For details about testing and the margin of error, refer to "Operation Check" in the meter/gauge system
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2. |
INSPECT STEREO COMPONENT AMPLIFIER ASSEMBLY |
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(a) Disconnect the I17 stereo component amplifier assembly connector. |
(b) Jack up the drive wheels.
(c) Move the shift lever to N.
(d) Turn the ignition switch to ON.
(e) Using an oscilloscope, check the signal waveform of the meter.
Waveform
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Terminal Connections |
I17-11 (SPD) - Body ground |
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Tester Range |
5 V/DIV., 20 msec./DIV. |
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Vehicle Condition |
Drive vehicle at 20 km/h (12 mph) |
HINT:
As the vehicle speed increases, the wavelength shortens.
OK:
Voltage pulses as shown in the illustration.
(f) Reconnect the stereo component amplifier assembly connector.
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3. |
CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - STEREO COMPONENT AMPLIFIER) |
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(a) Disconnect the I17 stereo component amplifier assembly connector. |
(b) Disconnect the H37 combination meter assembly connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
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Tester Connection |
Switch Condition |
Specified Condition |
|---|---|---|
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I17-11 (SPD) - H37-35 (+S) |
Always |
Below 1 Ω |
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I17-11 (SPD) - Body ground |
Always |
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 an ECU that is connected to the SPD signal wire.
(d) Reconnect the stereo component amplifier assembly connector.
(e) Reconnect the combination meter assembly connector.
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