Toyota Camry (XV70): Speed Signal Malfunction (B15C2)

DESCRIPTION

The navigation ECU receives a vehicle speed signal from the combination meter assembly and information from the navigation antenna assembly, and then adjusts the vehicle position on the map.

The navigation ECU stores this DTC when the difference between the speed information that the navigation antenna assembly receives and the SPD pulse received from the combination meter assembly becomes large.

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 its respective system based on this 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

CAUTION / NOTICE / HINT

NOTICE:

• Depending on the parts that are replaced during vehicle inspection or maintenance, performing initialization, registration or calibration may be needed. Refer to Precaution for Navigation System.

  Click here

• When replacing the radio and display receiver assembly or navigation ECU, always replace it with a new one. If a radio and display receiver assembly or navigation ECU which was installed to another vehicle is used, the following may occur:
  • A communication malfunction DTC may be stored.
  • The radio and display receiver assembly or navigation ECU may not operate normally.

PROCEDURE

(a) Clear the DTCs.

(b) Recheck for DTCs and check that no DTCs are output.

OK:

No DTCs are output.

OK

USE SIMULATION METHOD TO CHECK

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(a) Enter the "System Sensors Check" screen. Refer to Check GPS & Vehicle Sensors in Operation Check. Click here

(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 procedure inspection referring to values in the Data List of the skid control ECU because it is the source of the vehicle speed signal.

OK:

Vehicle speed displayed on the "System Sensors Check" screen is almost the same as the actual vehicle speed measured using the Techstream.

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OK

GO TO STEP 5

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(a) Check the output waveform. (1) Remove the combination meter assembly with the connector(s) still connected. (2) Connect an oscilloscope to terminal K21-6 (+S) and body ground. (3) Turn the engine switch on (IG). (4) Turn a wheel slowly. (5) Check the signal waveform according to the condition(s) in the table below. Item Condition Measurement terminal K21-6 (+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. 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.

*a Component with harness connected (Combination Meter Assembly)

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GO TO METER / GAUGE SYSTEM

OK

(a) Disconnect the K17 navigation ECU connector.

(b) Disconnect the K21 combination meter assembly connector.

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

Standard Resistance:

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REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

(a) Replace the navigation ECU with a new one.

Click here

NEXT

(a) Clear the DTCs.

(b) Recheck for DTCs and check that no DTCs are output.

OK:

No DTCs are output.

OK

END (NAVIGATION ECU IS DEFECTIVE)

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REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY

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