| Last Modified: 11-29-2007 | 1.6 J | |
| Service Category: Audio/Visual/Telematics | Section: Audio/Video | |
| Model Year: 2008 | Model: Sequoia | Doc ID: RM0000020S0017X |
| Title: AUDIO / VIDEO: AUDIO AND VISUAL SYSTEM: DESCRIPTION (2008 Sequoia) | ||
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Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter |
DESCRIPTION
This circuit is necessary for the ASL (Auto Sound Leveliser) built into the radio receiver.
Speed signals are received from the combination meter 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. The signal is changed to a pulse signal at the transistor in the combination meter. 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 is normal.
OK:
Actual vehicle speed and the speed indicated on the speedometer are the same.
HINT:
-
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
.
- The vehicle speed sensor is functioning normally when the indication on the speedometer is normal.
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2. |
INSPECT COMBINATION METER ASSEMBLY (SPEED SIGNAL) |
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(a) Disconnect the I3*1 or I9*2 radio receiver assembly connector. HINT:
*1: for 8 Speakers HINT: *2: for 14 Speakers |
(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 combination meter assembly.
Waveform
|
Terminal Connection |
I3-3(SPD)*1 - Body ground I9-4(SPD)*2 - Body ground |
|
Tester Range |
5 V/DIV., 20 msec./DIV |
|
Vehicle Condition |
Drive vehicle at 20 km/h (12 mph) |
HINT:
- *1: for 8 Speakers
- *2: for 14 Speakers
- As the vehicle speed increases, the wavelength shortens.
OK:
Voltage pulses as shown in the illustration.
(f) Reconnect the radio receiver assembly connector.
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3. |
CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - RADIO RECEIVER ASSEMBLY) |
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(a) Disconnect the I3*1 or I9*2 radio receiver assembly connector. HINT:
*1: for 8 Speakers HINT: *2: for 14 Speakers |
(b) Disconnect the H37 combination meter assembly connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
for 8 Speakers
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
I3-3 (SPD) - H37-35 (+S) |
Always |
Below 1 Ω |
|
I3-3 (SPD) - Body ground |
Always |
10 kΩ or higher |
for 14 Speakers
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
I9-4 (SPD) - H37-35 (+S) |
Always |
Below 1 Ω |
|
I9-4 (SPD) - Body ground |
Always |
10 kΩ or higher |
(d) Reconnect the radio receiver assembly connector.
(e) Reconnect the combination meter assembly connector.
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