Vehicle Speed Signal Circuit Between Radio Receiver and Combination Meter

AUDIO / VISUAL: AUDIO AND VISUAL SYSTEM (for Regular Cab and Double Cab): Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter

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

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 Operation Check.
- The vehicle speed sensor is functioning normally when the indication on the speedometer is normal.

NG -- GO TO METER / GAUGE SYSTEM
OK -- Continue to next step.
2. INSPECT RADIO RECEIVER




(a) Disconnect the K3*1 or K9*2 receiver connector.
HINT:
- *1: for Built-in Type Amplifier System
- *2: for Separate Type Amplifier System
(b) Measure the voltage.
(1) Jack up the drive wheels.
(2) Move the shift lever to the neutral position.
(3) Turn the ignition switch to the ON position.





(4) Measure the voltage between terminal SPD of the wire harness connector and body ground when the drive wheels are turned slowly.
OK:
Voltage pulses as shown in the illustration.






C -- REPLACE RADIO RECEIVER
B -- REPLACE RADIO RECEIVER
A -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (COMBINATION METER - RADIO RECEIVER)




(a) Disconnect the K3*1 or K9*2 receiver connector.

HINT:
- *1: for Built-in Type Amplifier System
- *2: for Separate Type Amplifier System
(b) Disconnect the J28 meter connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:
for Separate Type Amplifier System






for Built-in Type Amplifier System






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE COMBINATION METER