Last Modified: 04-05-2023 6.11:8.1.0 Doc ID: RM100000000VJ4L
Model Year Start: 2016 Model: Sienna Prod Date Range: [12/2015 - 11/2017]
Title: AUDIO / VIDEO: AUDIO AND VISUAL SYSTEM: Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter; 2016 - 2017 MY Sienna [12/2015 - 11/2017]

Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter

DESCRIPTION

Audio function:

This circuit is necessary for the automatic sound levelizer (ASL) built into the radio and display receiver assembly.

ASL function:

Speed signals are received from the combination meter assembly and used for the ASL.

The ASL function automatically adjusts the sound volume in order to maintain 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 connected to the combination meter assembly, 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 the pulse signal.
  • If a short occurs in any of the ECU or in the wire harness connected to an ECU, related components will not operate normally.

WIRING DIAGRAM

PROCEDURE

1.

CHECK VEHICLE SIGNAL

(a) Enter the "Vehicle Signal Check Mode" screen. [Refer to Check Vehicle Signal Check Mode in Operation Check (See page 2016 - 2017 MY Sienna [12/2015 - 11/2017]; AUDIO / VIDEO: AUDIO AND VISUAL SYSTEM: OPERATION CHECK )]

(b) While driving the vehicle, compare the value of "SPEED" to the reading on the speedometer.

(1) Check if these readings are almost equal.

OK:

Vehicle speed displayed on the "Vehicle Signal Check Mode" screen is almost the same as the reading on the speedometer.

OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

(See page 2016 MY Sienna [12/2015 - 08/2016]; AUDIO / VIDEO: AUDIO AND VISUAL SYSTEM: PROBLEM SYMPTOMS TABLE 2017 MY Sienna [08/2016 - 11/2017]; AUDIO / VIDEO: AUDIO AND VISUAL SYSTEM: PROBLEM SYMPTOMS TABLE )

NG

2.

CHECK HARNESS AND CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY - COMBINATION METER ASSEMBLY)

(a) Disconnect the D155 radio and display receiver assembly connector.

(b) Disconnect the D145 combination meter assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

D155-17 (SPD) - D145-35 (+S)

Always

Below 1 Ω

D155-17 (SPD) - Body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.

INSPECT COMBINATION METER ASSEMBLY (SPEED SIGNAL)

(a) Check the input waveform.

(1) Remove the combination meter assembly with the connector(s) still connected.

(2) Connect an oscilloscope to terminal D145-3 (+S) and body ground.

(3) Turn the ignition switch to ON.

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

Measurement Condition

Item

Condition

Terminal No. (Symbol)

D145-3 (+S) - Body ground

Tool setting

5 V/DIV., 20 ms./DIV.

Condition

Being driven at approximately 20 km/h (12 mph)

OK:

The waveform displayed is as shown in the illustration.

Text in Illustration

*a

Component with harness connected

(Combination Meter Assembly)

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

REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY

NG

GO TO METER / GAUGE SYSTEM