Page 1073 of 1449
ABS <4WD> -General Information/Service Specifications35B-3
CONSTRUCTION DIAGRAM
Stop lamp
switch*Parking brake
switch
Diagnosis
connector*
Wheel speed sensorWheel speed sensor Hydraulic unit
assembly*
(integrated with
the ABS-ECU) ABS warning lamp
Lateral G sensor
Longitudinal G sensor Steering
wheel
sensor*
NOTE
For R.H. drive vehicles, only the position indicated by the * is symmetrical.
SERVICE SPECIFICATIONS
ItemsStandard value
Wheel speed sensor internal resistance kΩ1.24 - 1.64
Wheel speed sensor insulation resistance kΩ100 or more
Lateral G sensor/Longitudinal G
sensoroutputvoltageV
On stationary vehicle2.4 - 2.6
sensor outputvoltageV
With front mark downward3.4 - 3.6
Page 1074 of 1449

ABS <4WD> -Special Tools/Troubleshooting35B-4
SPECIAL TOOLS
ToolNumberNameUse
MB991502MUT-IIsub
assemblyFor checking of ABS
(Diagnosis code display when using the
MUT-II)
MB991529Diagnosis code
check harnessFor checking of ABS
(Diagnosis code display when using the ABS
warning lamp)
MB991348Test harness setFor checking of G sensor
TROUBLESHOOTING
STANDARD FLOW OF DIAGNOSTIC TROUBLESHOOTING
Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points.
NOTES WITH REGARD TO DIAGNOSIS
1. The phenomena listed in the following table are not abnormal.
PhenomenonExplanation of phenomenon
System check soundWhen starting the engine, a thudding sound can sometimes be heard coming from inside
the engine compartment, but this is because the system operation check is being
performed, and is not an abnormality.
ABS operation sound1. Sound of the motor inside the ABS hydraulic unit operation. (whine)
2. Sound is the generated along with vibration of the brake pedal. (scraping)
3. When ABS operates, sound is generated from the vehicle chassis due to repeated
brake application and release.
(Thump: suspension; squeak: tyres)
System check soundWhen depressing the brake pedal during driving, a shock is sometime felt.
2. For road surfaces such as snow-covered roads and gravel roads, the braking distance for vehicles
with ABS can sometimes be longer than that for other vehicles. Accordingly, advise the customer
to drive safely on such roads by lowering the vehicle speed and not being too overconfident.
3. Diagnosis detection condition can vary depending on the diagnosis code.
Make sure that checking requirements listed in the “Comment” are satisfied when checking the trouble
symptom again.
Page 1075 of 1449

ABS <4WD> -Troubleshooting35B-5
ABS WARNING LAMP INSPECTION
Check that the ABS warning lamp illuminates as follows.
1. When the ignition key is turned to “ON”, the ABS warning
lamp illuminates for approximately 3 seconds and then
switches off.
2. When the ignition key is turned to “START”, the ABS
warning lamp remains illuminated.
3. When the ignition key is turned from “START” back to
“ON”, the ABS warning lamp illuminates for approximately
3 seconds and then switches off.
NOTE
The ABS warning lamp may remain on until the vehicle
reaches a speed of several km/h. This is limited to cases
where diagnosis code Nos.21 to 24, 41 to 44, 53 or 55
have been recorded because of a previous problem
occurring. In this case, the ABS-ECU keeps the warning
lamp illuminated until the problem corresponding to that
diagnosis code can be detected.
4. If the illumination is other than the above, check the
diagnosis codes.
DIAGNOSIS FUNCTION
READING DIAGNOSIS CODES
Read a diagnosis code by the MUT-IIor ABS warning lamp.
(Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points.)
NOTE
Connect the MUT-IIto the diagnosis connector (16-pin).
ERASING DIAGNOSIS CODES
When using the MUT-II
Connect the MUT-IIto the diagnosis connector (16-pin) and
erase the diagnosis code.
Caution
Turn the ignition key to the “LOCK” (OFF) position before
connecting or disconnecting the MUT-II.
Not
illuminated
ABS
warn-
ing
lampIlluminated
Approx. 3 sApprox. 3 s
Ignition
switchSTARTON
ACC,
ABS warning lamp
Page 1076 of 1449
ABS <4WD> -Troubleshooting35B-6
When not using the MUT-II
NOTE
If the ABS-ECU function has been stopped because of fail-safe
operation, it will not be possible to erase the diagnosis codes.
1. Stop the engine.
2. Use the special tool to earth terminal (1) (diagnosis control
terminal) of the diagnosis connector.
3. Turn on the stop lamp switch. (Depress the brake pedal.)
4. After carrying out steps 1. to 3., turn the ignition switch
to “ON”. Within 3 seconds after turning the ignition switch
to “ON”, turn off the stop lamp switch (release the brake
pedal). Then, turn the stop lamp switch on and off a
total of 10 times.
1st2nd3rd4th5th6th7th8th9th10th
Within
1
secondWithin
1
secondWithin
1
secondWithin
1
secondWithin
1
secondWithin
1
secondWithin
1
secondWithin
1
secondWithin
1
secondWithin
1
second
1 second
Ignition switchON
LOCK (OFF)
Stop lamp switchON
OFF
ABS warning lampON
OFF
ABS-ECU memory
Within 3
seconds
Erasing of ABS-ECU
diagnosis codes complete.
MB991529
Page 1077 of 1449

ABS <4WD> -Troubleshooting35B-7
INSPECTION CHART FOR DIAGNOSIS CODES
Diagnosis code No.Inspection itemReference page
11Front right wheel speed sensor (Open circuit or short circuit)35B-9
12Front left wheel speed sensor (Open circuit or short circuit)
13Rear right wheel speed sensor (Open circuit or short circuit)
14Rear left wheel speed sensor (Open circuit or short circuit)
16*ABS-ECU power supply system (Abnormal voltage drop or rise)35B-10
21Front right wheel speed sensor35B-9
22Front left wheel speed sensor
23Rear right wheel speed sensor
24Rear left wheel speed sensor
32Longitudinal G sensor system35B-11
41Front right solenoid valveThe diagnosis codes are output
whenthereisnoresponsetothe
35B-12
42Front left solenoid valve
whenthereis no responsetothe
drive signals for respective solenoid
valvesortheABS ECUpower43Rear right solenoid valvevalves or theABS-ECUpower
supply system is defective.
44Rear left solenoid valve
51Valve relay problem (stays on)35B-30, 31
(Replace the
hydraulic unit and
ABS-ECU.)
52Valve relay problem (stays off) or ABS-ECU power supply system
problem35B-12
53Motor relay problem (stays off) or ABS-ECU power supply system
problem
54Motor relay problem (stays on)35B-30, 31
(Replace the
hydraulic unit and
ABS-ECU.)
55Motor system (seized pump motor) or ABS-ECU power supply system
problem35B-12
63ABS-ECU35B-30, 31
(Replace the
hydraulic unit and
ABS-ECU.)
71Lateral G sensor system35B-13
Page 1078 of 1449
ABS <4WD> -Troubleshooting35B-8
Diagnosis code No.Reference page Inspection item
81Steering wheel sensor (ST-1) system (Open circuit or short circuit)35B-14
82Steering wheel sensor (ST-2) system (Open circuit or short circuit)
83Steering wheel sensor (ST-N) system (Open circuit or short circuit)
NOTE: diagnosis code No.16, 52, 63
1. Code No. 16 is cleared from the memory by turning the ignition switch to ACC position. When the system
is properly reset, this code is also cleared from the memory.
2. Code No. 52 and 63 are cleared from the memory by turning the ignition switch to ACC position.
Page 1079 of 1449

ABS <4WD> -Troubleshooting35B-9
INSPECTION PROCEDURE FOR DIAGNOSIS CODES
Code Nos.11, 12, 13 and 14 Wheel speed sensor
(open circuit or short circuit)Probable cause
Code Nos.21, 22, 23 and 24 Wheel speed sensor
Code Nos. 11, 12, 13 and 14 are output if the ABS-ECU detects an open circuit
or short-circuit in the (+) wire or ( - ) wire in any one of the four wheel speed sensors.DMalfunction of wheel speed sensor
DMalfunction of wiring harness or connector
DMalfunction of hydraulic unit and ABS-ECU
Code Nos. 21, 22, 23 and 24 are output in the following cases.
DWhen there is no input from any one of the four wheel speed sensors when travelling
at several km/h or more, even though open circuit can not be verified.
DWhen a chipped or blocked-up ABS rotor is detected and if the anti-lock system
operates continuously because a malfunctioning sensor or a warped ABS rotor
is causing sensor output to drop.DMalfunction of wheel speed sensor
DMalfunction of wiring harness or connector
DMalfunction of ABS rotor
DToo much gap between the sensor and the ABS rotor
DMalfunction of hydraulic unit and ABS-ECU
DMalfunction of wheel bearing
NG
NG
Replace
OK
Check the harness wire, and repair if necessary.
DBetween each wheel speed sensor and ABS-ECU
NG
Repair
OK
Wheel bearing check
(Refer to GROUP 26 and
GROUP 27 - On-vehicle
Service.)
NG
Repair
NG
Replace the hydraulic unit and ABS-ECU.
OK
Check the trouble
symptom.
Check the following connector:B-123
OK
ABS rotor check
(Refer to P.35B-34.)NG
Replace
NG
Wheel speed sensor
check
(Refer to P.35B-34.)NG
Replace
OK
Wheel speed sensor output voltage check (Refer to P.35B-26.)OK
Check the trouble
symptom.
OK
Check the following connectors:
A-03, A-37, A-43 , C-111, C-128, C-136
drive vehicles>, C-146, D-04, D-10, D-30
OK
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 kΩNGWheel speed sensor check (Refer to P.35B-34.)
Wheel speed sensor installation checkNG
Repair
Page 1080 of 1449

ABS <4WD> -Troubleshooting35B-10
Code No.16 ABS-ECU power supply system (abnormal
voltage drop or rise)Probable cause
This code is output if the ABS-ECU power supply voltage drops below or rises above
the rated values.
Furthermore, turning the ignition switch to ACC will erase this code.DMalfunction of battery
DMalfunction of wiring harness or connector
DMalfunction of hydraulic unit and ABS-ECU
Caution
If battery voltage drops or rises during inspection, this code will be output as well. If the voltage
returns to standard value, this code is no longer output.
Before carrying out the following inspection, check the battery level, and refill it if necessary.
NGNG
Repair
NG
Replace the hydraulic unit and ABS-ECU.
NG
Repair
Check the harness wire, and repair if necessary.
DBetween ignition switch (IG2) and ABS-ECU
OK
Check the trouble
symptom.
OK
Check the trouble
symptom.
OK
Check the following connector:B-123
NGCheck the following connectors:B-123, C-128
vehicles>, C-130 , C-209, C-210Measure at the ABS-ECU connector B-123.
DDisconnect the connector, and measure at the harness side
connector.
DStart the engine. Voltage between 10 and body earth
OK:System voltage