ABS <4WD> -Troubleshooting35B-17
Inspection Procedure 2
Communication between MUT-IIand the ABS-ECU is not
possible.
Probable cause
The cause may be an open circuit in the ABS-ECU power supply circuit or an open
circuit in the diagnosis output circuit.DBlown fuse
DMalfunction of wiring harness or connector
DMalfunction of hydraulic unit and ABS-ECU
NG OK
NG
NG NG
Repair
Check the harness wire, and repair if necessary.
DBetween ABS-ECU and diagnosis connector
OK
NG
Repair
NG
Check the harness wire, and repair if necessary.
DBetween ignition switch (IG2) and ABS-ECU
OK
NG
Repair
NG
Check the harness wire, and repair if necessary.
DBetween ABS-ECU and earth
NG
Repair
NG
Replace the hydraulic unit and ABS-ECU.
OK
Check the trouble
symptom.
OK
Check the trouble
symptom.
OK
Check the following connector:B-123
Measure at the ABS-ECU connector B-123.
DDisconnect the connector, and measure at the harness side
connector.
DContinuity between 12 and body earth, and between 34 and
body earth
OK:ContinuityCheck the following connector:B-123
OK
Check the trouble
symptom.
Measure at the ABS-ECU connector B-123.
DDisconnect the connector, and measure at the harness side
connector.
DIgnition switch: ON
DVoltage between 10 and body earth
OK:System voltageCheck the following connectors:B-123, C-128
Check the trouble
symptom.
Measure at the diagnosis connector C-22 and the ABS-ECU
connector B-123.
DDisconnect the connectors, and measure at the harness side
connectors.
DContinuity between the following terminals
ABS-ECU side - Diagnosis connector side
5-1
2-7
OK:ContinuityNGCheck the following connectors:
B-123, C-22, C-26, C-28
ABS <4WD> -Troubleshooting35B-18
Inspection Procedure 3
When the ignition key is turned to “ON” (engine stopped),
the ABS warning lamp does not illuminate.
Probable cause
The cause may be an open circuit in the lamp power supply circuit, a blown lamp,
or an open circuit between the ABS warning lamp and the earth.DBlown fuse
DBurn out ABS warning lamp bulb
DMalfunction of combination meter
DMalfunction of wiring harness or connector
DMalfunction of hydraulic unit and ABS-ECU
NO
NG
Replace the ABS warning lamp bulb.
Check the harness wire.
DBetween combination meter and ABS-ECU
DBetween ignition switch (IG1) and combination meter
DBetween combination meter and earth
Replace the hydraulic unit and ABS-ECU.
OKNG
OK
Check the following connectors:
B-123, C-01, C-29
OK
Check whether the ABS warning lamp bulb is burnt out.
Does the ABS warning lamp illuminate when the ABS-ECU
connector B-123 is disconnected and the ignition switch is turned
to ON?YES
Repair
Replace the combination meter. (Refer to GROUP 54A.)NG
Repair
Inspection Procedure 4
Even after the engine is started, the ABS warning lamp
remains illuminated.
Probable cause
The cause is probably a short-circuit in the ABS warning lamp illumination circuit.DMalfunction of combination meter
DMalfunction of wiring harness (short circuit)
DMalfunction of hydraulic unit and ABS-ECU
NOTE
This trouble symptom is limited to cases where communication with the MUT-IIis possible (ABS-ECU
power supply is normal) and the diagnosis code is a normal diagnosis code.
YES
NG
Check the harness wire.
DBetween combination meter and ABS-ECU
Replace the hydraulic unit and ABS-ECU.
OK
NG
OK
Check the trouble symptom.
Does the ABS warning lamp stay illuminated when the ABS-ECU
connector B-123 is disconnected and the ignition switch is turned
to ON?NO
Repair
Replace the combination meter. (Refer to GROUP 54A.)NG
Repair
Check the following connectors:B-123, C-01, C-128
ABS <4WD> -Troubleshooting35B-19
Inspection Procedure 5
In the inspection by MUT-II service data, the parking brake
switch is not turned ON or turn OFF.
Probable cause
ABS-ECU optimizes the ABS control when pulling the parking brake lever, parking
brake switch signal is used as support. If there is a fault in the parking brake switch
system, ABS control is not optimized.DMalfunction of parking brake switch
DMalfunction of wiring harness or connector
DMalfunction of hydraulic unit and ABS-ECU
OK
NG
NG
Check the harness wire.
DBetween parking brake switch and ABS-ECU
Replace the hydraulic unit and ABS-ECU.
OK
NG
OK
Check the trouble symptom.
Repair
NG
RepairCheck the following connectors:B-123, C-26, C-128
Measure at the ABS-ECU connector B-123.
DDisconnect the connector, and measure at the harness side
connector.
DMeasure by pulling or releasing the parking brake lever.
DContinuity between 1 and body earth
OK:Continuity
OK:No continuity
NG
Repair
NG
OK
Check the trouble
symptom.
Check the following connector:B-123
OK
Replace the parking brake switch. (Refer to GROUP 36.)
NG
RepairCheck the parking brake switch installation condition.
ABS <4WD> -Troubleshooting35B-20
Inspection Procedure 6
The neutral position learning of the steering wheel sensor
is not finished.
Probable cause
The diagnosis is difficult because it depends on driving condition and road surface,
if the diagnosis code displays the normal code, carry out the following check.DEquipment the odd diameter tyre
DMalfunction of suspension
DMalfunction of steering wheel sensor installation
DMalfunction of stop lamp switch system
DMalfunction of hydraulic unit and ABS-ECU
NG
NG
NG
NG
Check the harness wire, and repair if necessary.
DBetween battery and stop lamp switch
DBetween stop lamp switch and ABS-ECU
OK
Check the trouble
symptom.
OK
Check the following connectors:B-123, C-103, C-108, C-130,
C-135
OK
Check the stop lamp switch. (Refer to GROUP 35A - Brake Pedal.)
Check the stop lamp switch installation condition.
(Refer to GROUP 35A - On-vehicle Service.) NO
Repair
OKNG
RepairOKNG
RepairReplace
NG
Replace the hydraulic unit
and ABS-ECU.
NG
Check the harness wire,
and repair if necessary.
DBetween stop lamp
switch and ABS-ECURepair
Check the trouble
symptom.
NG
Check the following
connectors:
C-108, C-130
Check the trouble
symptom.
OK
Check the following
connector:B-123
YES
Measure at the ABS-ECU connector B-123.
DDisconnect the connector, and measure at the harness side
connector.
DStop lamp switch: ON
DVoltage between 19 and body earth
OK:System voltage
Does the stop lamp turn on and off normally?
YES
Repair
NO
Is the odd diameter tire equipped?
YES
Repair
NO
Is the suspension abnormal?
NO
YES
When the steering wheel position is neutral, does the steering wheel
sensor (ST-N) turn ON in the MUT-II service data?Check the steering wheel sensor and the steering wheel installation
condition.
ABS <4WD> -Troubleshooting35B-21
Inspection Procedure 7
Faulty ABS operation
Probable cause
This varies depending on the driving conditions and the road surface conditions, so
problem diagnosis is difficult. However, if a normal diagnosis code is displayed, carry
out the following inspection.DImproper installation of wheel speed sensor
DMalfunction of wiring harness or connector
DMalfunction of wheel speed sensor
DMalfunction of ABS rotor
DForeign material adhering to wheel speed sensor
DMalfunction of wheel bearing
DMalfunction of hydraulic unit and ABS-ECU
OK
OK
Check the following connector:B-123
NG
Measure at the ABS-ECU connector B-123.
DDisconnect the connector, and measure at the harness side
connector.
DResistances between 6 and 7, 8 and 9, 22 and 31, 29 and
30
OK:1.24 - 1.64 kΩ
(The sensor harness and connector should be moved while
these inspections are carried out.)NG
OK
Check the trouble symptom.
OK
NG
Repair
OK
Wheel bearing check (Refer to GROUP 26 and GROUP 27 -
On-vehicle Service.)NG
Repair
OK
ABS rotor check (Refer to P.35B-34.)NG
Repair
NG
Wheel speed sensor check (Refer to P.35B-34.)NGReplace the wheel speed sensor.
OK
Wheel speed sensor output voltage check (Refer to P.35B-26.)OKHydraulic unit check (Refer to P.35B-28.)
Wheel speed sensor installation checkNG
Repair
Check the harness wire.
DBetween each wheel speed sensor and ABS-ECU
NG
Repair
NG
NG
RepairOK
Check the following connectors:B-123, C-128
NG
Check the trouble symptom.
RepairNG
OK
Check the harness wire.
DBetween 4WD-ECU and ABS-ECU OK
Measure at the 4WD-ECU connector C-43.
DDisconnect the connector, and measure at the harness side
connector.
DCarry out the ABS signal of the actuator test from the ABS
menu of the MUT-II.
DVoltage between 49 and body earth
OK:Less than 1.0V for initial 10 seconds, then system voltage
NGABS signal check
DDisplay the ABS signal of the service data from ACD (4WD)
menu of MUT-II.
OK:Displays OFF
DBrake in safety area, operate the ABS (possible to inspect
in first velocity of approx. 30km/h)
OK:Displays ON (in operating ABS)
NG
Check the trouble symptom.
Replace the hydraulic unit and ABS-ECU.
Check the following connectors:
A-03, A-37, A-43
ABS <4WD> -Troubleshooting35B-22
DATA LIST REFERENCE TABLE
The following items can be read by the MUT-IIfrom the ABS-ECU input data.
1. When the system is normal
Item No.Check itemChecking requirementsNormal value
11Front-right wheel speed sensorPerform a test runVehicle speeds
displayedonthe
12Front-left wheel speed sensor
displayedonthe
speedometer and
MUTIIareidentical13Rear-right wheel speed sensorMUT-IIareidentical.
14Rear-left wheel speed sensor
21Power supply voltageIgnition switch: ON10 - 16 V
29Parking brake switchPull the parking brake lever.ON
Release the parking brake lever.OFF
36Stop lamp switchDepress the brake pedal.ON
Release the brake pedal.OFF
37Steering wheel sensor neutral
position learningAfter driving straightly with vehicle speed more
than 10km/hON
Before driving with ignition switch ONOFF
71Lateral G sensorWhen vehicle stops2.4 - 2.6 V
When vehicle drives1.0 - 4.0 V
74Steering wheel sensor (ST-N)Ignition switch: ONSteering:
Neutral position and
position near by±
360_ON
Steering:
Except for aboveOFF
75Steering wheel sensor (ST-1)Ignition switch: ONSteering:
Turnlaterallyslowly
Display ON and OFF
alternately
76Steering wheel sensor (ST-2)
Turnlaterallyslowlyalternately
86Steering degreeIgnition switch: ON
Steering wheel sensor
tlitili
Steering: Steer by
90_to the right+90_
g
neutral position learning
is finished (service data
N37di lON)
Steering: NeutralOFF(
No. 37 displays ON)Steering: Steer by
90_to the left-90_
2. When the ABS-ECU shut off ABS operation
When the diagnosis system stops the ABS-ECU, the MUT-IIdisplay data will be unreliable.
ABS <4WD> -Troubleshooting35B-23
ACTUATOR TEST REFERENCE TABLE
The MUT-IIactivates the following actuators for testing.
NOTE
1. If the ABS-ECU runs down, actuator testing cannot be carried out.
2. Actuator testing is only possible when the vehicle is stationary.
ACTUATOR TEST SPECIFICATIONS
Item
No.Checking itemActivation
01Solenoid valve for front-right
wheelSolenoid valves and
pump motors in the
hd liit(i l02Solenoid valve for front-left
wheel
pp
hydraulic unit (simple
inspection mode)
03Solenoid valve for rear-right
wheel
04Solenoid valve for rear-left
wheel
05ABS signalABS signal (voltage:
less than 1.0V) is
output for 10 seconds
2s
1s
0.05 s0.01 s
Activation pattern of Items No. 01 - 04
Solenoid
valve
Pump
motorON
OFFStart of
forced action
End of forced
action
A
B
C
NOTE
A: Hydraulic pressure increase
B: Hydraulic pressure holds
C: Hydraulic pressure decrease
ABS <4WD> -Troubleshooting35B-24
CHECK AT ABS-ECU
Use the following steps to remove the connector cover and
measure the terminal voltage.
1. Move the lock lever of the ABS-ECU connector as shown
in the illustration, and then disconnect the ABS-ECU
connector.
2. Push up and unlock the hooks of the ABS-ECU connector
shown in the illustration, then remove the connector cover.
TERMINAL VOLTAGE CHECK CHART
1. Measure the voltage between each terminal and earth
(terminal No.12).
2. The terminal layout is shown in the illustration.
Terminal No.Check itemChecking requirementsNormal condition
1Parking brake switch
input
Parking brake switch: ON1 V or less
input
Parking brake switch: OFFSystem voltage
2MUT-IIWhen the MUT-IIis connectedSerial communication with MUT-II
When the MUT-IIis not connected1 V or less
3ABS ON output to
4WD ECU
With ABS active (reference)(0.5 V or less)
4WD-ECU
With ABS not activeSystem voltage
4Steering wheel sensor
(ST-N) inputIgnition
switch: ONSteering wheel: Neutral
position and position
near by±360_0.8 - 2.1 V
Steering wheel: Except
for above2.7 - 4.4 V
5Diagnosis changeover
input
When the MUT-IIis connected0V
input
When the MUT-IIis not connectedApprox. 12 V
Lock lever