Inspection Procedure

WARNING: This page is about a different variant/trim than selected.

HINT:

Check the condition of each related circuit connector before troubleshooting (See ELECTRONIC CIRCUIT INSPECTION PROCEDURE ).

CHECK DTC

Clear the DTC (See DTC CHECK/CLEAR ).
Start the engine.

Drive the vehicle, accelerating to a speed of 12 mph (20 km/h) or more and check if the speed sensor DTC (brake control system DTC) is output (See DTC CHECK / CLEAR ).

Result

RESULT DESCRIPTION

Result	Proceed to
No speed sensor DTC (brake control system DTC) is output	A
Speed sensor DTC (brake control system DTC) is output	B

B: REPAIR CIRCUITS INDICATED BY OUTPUT DTCS (BRAKE CONTROL SYSTEM)

A: Go to Next Step

READ VALUE OF TECHSTREAM

Connect the Techstream to the DLC3.
Start the engine.
Select the "Data List" on the Techstream (See DATA LIST / ACTIVE TEST ).

Check that the speed values detected at all four wheels displayed on the Techstream are the same when driving the vehicle.

HINT:

Drive the vehicle straight ahead.

DATA LIST: 4WD

DATA LIST 4WD

Item	Measurement Item / Range (Display)	Normal Condition
FR Wheel Speed	Wheel speed sensor (FR) reading / min.: 0 mph (0 km/h), max.: 202 mph (326.4 km/h)	Actual wheel speed
FL Wheel Speed	Wheel speed sensor (FL) reading / min.: 0 mph (0 km/h), max.: 202 mph (326.4 km/h)	Actual wheel speed
RR Wheel Speed	Wheel speed sensor (RR) reading / min.: 0 mph (0 km/h), max.: 202 mph (326.4 km/h)	Actual wheel speed
RL Wheel Speed	Wheel speed sensor (RL) reading / min.: 0 mph (0 km/h), max.: 202 mph (326.4 km/h)	Actual wheel speed

OK: The speed of all four wheels displayed on the Techstream should match.

NG: Go to step 4

OK: Go to Next Step

RECONFIRM DTC

Clear the DTC (See DTC CHECK/CLEAR ).
Start the engine.

Drive the vehicle, accelerating to a speed of 12 mph (20 km/h) or more and check if the same DTC is output.

Result

RESULT DESCRIPTION

Result	Proceed to
DTC is output	A
DTC is not output	B

B: CHECK INTERMITTENT PROBLEMS

A: REPLACE 4WD CONTROL ECU

CHECK HARNESS AND CONNECTOR (4WD CONTROL ECU TO SKID CONTROL ECU)

Disconnect the 4WD control ECU connector and skid control ECU connector.

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

Standard resistance

STANDARD RESISTANCE SPECIFICATIONS

Tester Connection	Specified Condition
A32-3 (FRO) - A14-37 (FRO)	Below 1 Ω
A32-16 (FLO) - A14-38 (FLO)	Below 1 Ω
A32-2 (RRO) - A14-39 (RRO)	Below 1 Ω
A32-15 (RLO) - A14-40 (RLO)	Below 1 Ω
A32-3 (FRO) - Body ground	10 kΩ or higher
A32-16 (FLO) - Body ground	10 kΩ or higher
A32-2 (RRO) - Body ground	10 kΩ or higher
A32-1S (RLO) - Body ground	10 kΩ or higher
A32-30 (GND) - Body ground	Below 1 Ω

Fig 1: Identifying 4WD Control ECU And Skid Control ECU Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to Next Step

INSPECT 4WD CONTROL ECU (INPUT SIGNAL OF VEHICLE SPEED)

Connect the 4WD control ECU connector.
Connect the oscilloscope to the 4WD control ECU.
Start the engine.

Fig 2: Identifying 4WD Control ECU Connector Terminals
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Check the signal waveform when the vehicle is driving.

Standard

TESTER CONNECTION AND SPECIFIED CONDITION

Tester Connection	Specified Condition
A32-3 (FRO) - A32-30 (GND)	Waveform is output
A32-16 (FLO) - A32-30 (GND)	Waveform is output
A32-2 (RRO) - A32-30 (GND)	Waveform is output
A32-15 (RLO) - A32-30 (GND)	Waveform is output

HINT:

As vehicle speed (wheel rotation speed) increases, the width of the waveform narrows.

Fig 3: Identifying Waveform Signal Reference Graph

WAVEFORM SIGNAL REFERENCE GRAPH

Item	Contents
Tool setting	2 V/DIV, 2 ms/DIV
Vehicle condition	Driving at approximately 18 mph (30 km/h)

Result

RESULT DESCRIPTION

Result	Proceed to
Waveform is normal	A
Waveform is not normal/Waveform is not output	B

B: REPLACE BRAKE CONTROL ACTUATOR ASSEMBLY (SKID CONTROL ECU)

A: REPLACE 4WD CONTROL ECU