Vehicle Speed Signal Circuit Between Radio Receiver and Combination Meter

AUDIO / VIDEO: AUDIO AND VISUAL SYSTEM (w/ Multi-display without DVD Player): Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter; 2013 MY Corolla [07/2012 -]
- Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter

DESCRIPTION

for Automatic Sound Levelizer (ASL):

* 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 combination meter assembly.

for "Bluetooth":

* Vehicle speed signals are received from the combination meter assembly and used to cancel "Bluetooth" function operation.

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

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 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

1. for TMC Made 2ZR-FE





2. except TMC Made 2AZ-FE





3. except TMC Made 2ZR-FE





INSPECTION PROCEDURE

PROCEDURE

1. CHECK VEHICLE SIGNAL (OPERATION CHECK)

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





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

HINT
The combination meter assembly 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 Techstream Data List / Active Test.

NG -- INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)

OK -- PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Problem Symptoms Table

2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)

(a) Check the output waveform.





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

(2) Connect an oscilloscope to terminal E46-36 (+S) and body ground.

(3) Turn the ignition switch to ON.

(4) Turn a wheel slowly.

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





OK:

The waveform is similar to that shown in the illustration.

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.

Text in Illustration





NG -- GO TO METER / GAUGE SYSTEM Speed Signal Circuit
OK -- Continue to next step.

3. INSPECT RADIO AND DISPLAY RECEIVER ASSEMBLY (INPUT WAVEFORM)

(a) Check the input waveform.





(1) Remove the radio and display receiver assembly with the connector still connected.

(2) Connect an oscilloscope to terminal E129-17 (SPD) and body ground.

(3) Turn the ignition switch to ON.

(4) Turn a wheel slowly.

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





OK:

The waveform is similar to that shown in the illustration.

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.

Text in Illustration





(b) Proceed to the next step based on the check result.

Result:





B -- REPAIR OR REPLACE HARNESS OR CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY - COMBINATION METER ASSEMBLY)

C -- REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY Removal
A -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY - NO. 4 JUNCTION BLOCK)

(a) Disconnect the E129 radio and display receiver assembly connector.

(b) Disconnect the 4A No. 4 junction block connector.

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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY - NO. 4 JUNCTION BLOCK)

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (NO. 4 JUNCTION BLOCK)