Toyota Tacoma 2015-2018 Service Manual: Speed Signal Malfunction (B15C2)

Toyota Tacoma 2015-2018 Service Manual / Navigation / Multi Info Display / Navigation System / Speed Signal Malfunction (B15C2)

DESCRIPTION

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

The navigation receiver assembly 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 the respective systems 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 diagram below will not operate normally.

DTC Code	DTC Detection Condition	Trouble Area
B15C2	A difference between the GPS speed and SPD pulse is detected.	Meter/gauge system Harness or connector Navigation receiver assembly

WIRING DIAGRAM

PROCEDURE

1.	CHECK VEHICLE SENSOR (OPERATION CHECK)

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

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

OK:

The readings are equal or almost equal.

REPLACE NAVIGATION RECEIVER ASSEMBLY

2.	CHECK COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)

(a) Check the output waveform.

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

(2) Connect an oscilloscope to terminal C9-40 (+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.

Item	Condition
Measurement terminal	C9-40 (+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.

Text in Illustration

*a	Component with harness connected (Combination Meter Assembly)

GO TO METER / GAUGE SYSTEM

3.	CHECK HARNESS AND CONNECTOR (NAVIGATION RECEIVER ASSEMBLY - COMBINATION METER ASSEMBLY)

(a) Disconnect the N25 navigation receiver assembly connector.

(b) Disconnect the C9 combination meter assembly connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
N25-17 (SPD) - C9-40 (+S)	Always	Below 1 Ω

REPLACE NAVIGATION RECEIVER ASSEMBLY

REPAIR OR REPLACE HARNESS OR CONNECTOR

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