NAVIGATION SYSTEM(for Radio and Display Type) Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter

DESCRIPTION

for Navigation Function:

The radio and display receiver assembly receives a vehicle speed signal from the meter circuit plate and sends the signal to the navigation ECU.

for Automatic Sound Levelizer (ASL) (for 6 Speakers):

This circuit is necessary for the Automatic Sound Levelizer (ASL) built into the radio and display receiver assembly.
The Automatic Sound Levelizer (ASL) function automatically adjusts the audio system volume level in order to compensate for increased vehicle noise (vehicle noise tends to increase as vehicle speed increases). The ASL adjusts the volume level based upon vehicle speed signals that it receives from the meter circuit plate.

for "Bluetooth":

Vehicle speed signals are received from the meter circuit plate and used to cancel "Bluetooth" function operation.

The radio and display receiver assembly recognizes that the vehicle is being to driven and makes it impossible to connect or register a "Bluetooth" device while driving.

Tech Tips

A voltage of 12 V or 5 V is output from each ECU and then input to the meter circuit plate. The signal is changed to a pulse signal at the transistor in the meter circuit plate. Each ECU controls the respective system based on the 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

CHECK VEHICLE SIGNAL (OPERATION CHECK)

Enter the "Vehicle Signal Check Mode" screen. Refer to Check Vehicle Signal Check Mode in Operation Check.

Click here

While driving the vehicle, compare the "SPEED" indicator to the reading on the speedometer. Check if these readings are almost equal.

Tech Tips

The meter circuit plate receives the vehicle speed signal from the skid control ECU via CAN communication. Therefore, perform the following inspection referring to values on the Data List of the skid control ECU because it is the source of the vehicle speed signal.

OK
Vehicle speed displayed on the "Vehicle Signal Check Mode" screen is almost the same as the actual vehicle speed measured using the GTS.
Click here Click here

Result

Proceed to
OK
NG

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

INSPECT METER CIRCUIT PLATE (OUTPUT WAVEFORM)

Check the output waveform.

Component with harness connected

(Meter Circuit Plate)

Remove the meter circuit plate with the connector still connected.
Connect an oscilloscope to terminal F6-19 (+S) and body ground.
Turn the power switch on (IG).
Turn a wheel slowly.

Check the signal waveform according to the condition(s) in the table below.

Item	Condition
Measurement terminal	F6-19 (+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.

Tech Tips

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.

Result

Proceed to
OK
NG

GO TO METER / GAUGE SYSTEM Click here

INSPECT RADIO AND DISPLAY RECEIVER ASSEMBLY (INPUT WAVEFORM)

Check the input waveform.

Component with harness connected

(Radio and Display Receiver Assembly)

Remove the radio and display receiver assembly with the connector still connected.
Connect an oscilloscope to terminal F31-17 (SPD) and body ground.
Turn the power switch on (IG).
Turn a wheel slowly.

Check the signal waveform according to the condition(s) in the table below.

Item	Condition
Measurement terminal	F31-17 (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.

Tech Tips

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.

Result

Result	Proceed to
OK	A
NG (for LHD)	B
NG (for RHD)	C

REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY Click here

CHECK HARNESS AND CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY - NO. 17 JUNCTION CONNECTOR) Click here

CHECK HARNESS AND CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY - NO. 11 JUNCTION CONNECTOR)

Disconnect the F31 radio and display receiver assembly connector.
Disconnect the F79 No. 11 junction connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance

Tester Connection	Condition	Specified Condition
F31-17 (SPD) - F79-10	Always	Below 1 Ω

Result

Proceed to
OK
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

CHECK HARNESS AND CONNECTOR (METER CIRCUIT PLATE - NO. 11 JUNCTION CONNECTOR)

Disconnect the F6 meter circuit plate connector.
Disconnect the F79 No. 11 junction connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance

Tester Connection	Condition	Specified Condition
F6-19 (+S) - F79-7	Always	Below 1 Ω

Result

Proceed to
OK
NG

REPAIR OR REPLACE NO. 11 JUNCTION CONNECTOR

REPAIR OR REPLACE HARNESS OR CONNECTOR

CHECK HARNESS AND CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY - NO. 17 JUNCTION CONNECTOR)

Disconnect the F31 radio and display receiver assembly connector.
Disconnect the F85 No. 17 junction connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance

Tester Connection	Condition	Specified Condition
F31-17 (SPD) - F85-18	Always	Below 1 Ω

Result

Proceed to
OK
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

CHECK HARNESS AND CONNECTOR (METER CIRCUIT PLATE - NO. 17 JUNCTION CONNECTOR)

Disconnect the F6 meter circuit plate connector.
Disconnect the F85 No. 17 junction connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance

Tester Connection	Condition	Specified Condition
F6-19 (+S) - F85-16	Always	Below 1 Ω

Result

Proceed to
OK
NG

REPAIR OR REPLACE NO. 17 JUNCTION CONNECTOR

REPAIR OR REPLACE HARNESS OR CONNECTOR