ECU MITSUBISHI MONTERO 2000 Service Repair Manual

BASIC BRAKE SYSTEM -Troubleshooting35A-12
Code No. 78 Accumulator system (Motor has
been energized abnormally for long time or
abnormal low-pressure accumulator)Probable cause
This code is output under the following cases:
DPump motor is operated for consecutive 300 seconds
DBrake fluid pressure is decreased, the HBB buzzer sounds due
to the operation of the pressure switch (for low pressure
warning), and then the brake warninglamp illuminates.DBrake fluid leaks inside the hydraulic brake booster (HBB)
DMalfunction of the HB motor relay
DMalfunction of connector or harness
DMalfunction of the ABS-ECU
DMalfunction of HBB (accumulator, pressure switch,pump motor or
master cylinder and hydraulic unit assembly)
NG
Repair
NG
OK
Check trouble symptom.
Repair NGNG
OK
Check trouble symptom.
Replace
OK
Check the following connectors:
B-17, B-18, B-19X, B-20X,
E-106, E-107
Check the harness wire:
DBetween fusible link No.9 and the motor relay
DBetween the motor relay and HBB
DBetween the HBB and the ABS-ECU
DBetween the HBB and the earthNG
Check the motor relay. (Refer to P.35A-24.)
NG
Replace the ABS-ECU. (Refer to GROUP 35B.)
Check trouble symptom.
NG
OKCheck the pressure switch. (Refer to P.35A-23.)NG
Replace
OKCheck the continuity and resistance of thepump motor.(Refer
to P.35A-23.)NG
Replace
OKVisually check the accumulator
Replace the master cylinder and hydraulic unit assembly.


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BASIC BRAKE SYSTEM -Troubleshooting35A-13
Code No.79 Pressure switch system (open or short
circuit)Probable cause
This code is output if the pressure switch circuit is short, ABS-ECU internal circuit
is defective, or the hydraulic brake booster (HBB) pressure switch or master cylinder
and hydraulic unit assembly is defective.DMalfunction of connector or harness
DMalfunction of the ABS-ECU
DMalfunction of the HBB (pressure switch or master
cylinder and hydraulic unit assembly)
NG
Repair
NG
OKRepair NG
OK
Check trouble symptom.
Check the following connectors:
B-17, B-18, E-106, E-107
Check the harness wire:
DBetween the HBB and the ABS-ECU
DBetween the HBB and the earthNG
Check trouble symptom.
Replace the ABS-ECU. (Refer to GROUP 35B.)
NG
OKCheck the pressure switch. (Refer to P.35A-23.)Replace the master cylinder and hydraulic unit assembly.
INSPECTION CHART FOR TROUBLE SYMPTOMS
Trouble symptomInspection
procedure
No.Reference page
The brake warning lamp does not illuminate when the ignition switch is turned ON
(engine stopped).135A-14
The brake warning lamp remains illuminated after the engine is started.235A-15
The HBB buzzer does not sound when the hydraulic brake booster (HBB) is
defective. (However, the brake warning lamp is illuminated.)335A-15
The HBB buzzer does not stop sounding.435A-16
Communication with MUT-II
is not possible.Refer to GROUP 35B.
Communication with MUT-II
and the ABS-ECU is not possible.


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BASIC BRAKE SYSTEM -Troubleshooting35A-14
Inspection procedure 1
The brake warning lamp does not illuminate when the
ignition switch is turned ON (engine stopped).
Probable cause
The cause may be anopencircuit in thelamppower supply circuit, a blown lamp,
a malfunction of the lampdrive transistor inside the ABS-ECU, anopencircuit between
the ignition switch and brake warninglamp or anshort circuit between the brake
warning lamp and theABS-ECU.DBlown fuse
DBurn out brake warninglamp bulb
DMalfunction of combination meter
DMalfunction of connector or harness
DMalfunction of ABS-ECU (lamp drive transistor)
Repair NG NG
NO
Replace the ABS-ECU. (Refer to GROUP 35B.)
Repair
Repair
NG
OK
Check for blown bulb.Replace the brake warninglamp bulb.
OK
Check the following connectors:
D-01, D-208, D-210 drive vehicles>, D-213
NG
Replace the combination meter. (Refer to GROUP 54.)
OK
Check trouble symptom.
OK
YES
Check multi-purpose fuse No.6.NGRefer to GROUP 00 – Inspection Procedure when a Fuse is blown.
Check the harness wire:
DBetween the ignition switch and the combination meter
Check the harness wire:
DBetween the combination meter and the ABS-ECU
Disconnect the ABS-ECU connector E-107. Does the brake warning
lamp illuminatewhen the ignition switch is turned ON?
NG
OK


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BASIC BRAKE SYSTEM -Troubleshooting35A-15
Inspection procedure 2
The brake warning lamp remains illuminated after the
engine is started.
Probable cause
The cause is probably malfunction of thelampdrive transistor inside the ABS-ECU
or an opencircuit between the brake warninglamp and theABS-ECU.DMalfunction of combination meter
DMalfunction of connector or harness
DMalfunction of ABS-ECU (lamp drive transistor)
NOTE
This trouble symptom is limited to cases where communication with the MUT-II is possible(ABS-ECU
power supply is normal) and the diagnosis code is a normal diagnosis code.
Repair NG
Repair
Replace the combination meter. (Refer to GROUP 54.)
OK
YESReplace the ABS-ECU. (Refer to GROUP 35B.)
NO
Disconnect the ABS-ECU connector E-107. Does the brake warning
lamp go outwhen the ignition switch is turned ON and No.39 terminal
is connected to the body earth.
OK
Check the following connectors:
D-01, E-13, E-107
Check trouble symptom.
Check the harness wire:
DBetween the combination meter and the ABS-ECUNG
NG
Inspection procedure 3
The HBB buzzer does not sound when the hydraulic brake
booster (HBB) is defective. (However, thebrake warning
lamp is illuminated.)
Probable cause
The cause is probably anopencircuit in the buzzer power supply circuit, a defective
buzzer, a malfunction of the buzzer drive transistor inside the ABS-ECU or anopen
circuit from the ignition switch through the HBB buzzer to the ABS-ECU.DBlown fuse
DMalfunction of the HBB buzzer
DMalfunction of connector or harness
DMalfunction of ABS-ECU (buzzer drive transistor)
Replace the ABS-ECU. (Refer to GROUP 35B.)
Repair NG
Repair
NG
OK
Check the HBB buzzer. (Refer to P.35A-40.)
OK
Check the following connectors:
D-32 ,
D-128, D-208, D-210 , D-213 vehicles>, E-08, E-13, E-107
NG
OK
Check trouble symptom.
Check multipurpose fuse No.5.NGRefer to GROUP 00 – Inspection Service Points for Blown Fuse.
Check the harnesse wire:
DBetween the ignition switch and the HBB buzzer
DBetween the HBB buzzer and the ABS-ECUNGReplace


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BASIC BRAKE SYSTEM -Troubleshooting35A-16
Inspection procedure 4
The HBB buzzer does not stop sounding.
Probable cause
The HBB buzzer circuit may be short.DMalfunction of the HBB buzzer
DMalfunction of the harness
DMalfunction of ABS-ECU (buzzer drive transistor)
NOTE
This trouble symptom is limited to cases where communication with the MUT-II
is possible (ABS-ECU
power supply is normal) and the diagnosis code is a normal diagnosis code.
OK
Repair NG
Repair
Replace the HBB buzzer.
OK
NG
YES
Replace the ABS-ECU. (Refer to GROUP 35B.)NODisconnect the ABS-ECU connector E-107. Does the HBB buzzer
remain sounding when the ignition switch is turned ON?
Check trouble symptom.
Check the harness wire:
DBetween the HBB buzzer and the ABS-ECUNG
Check the following connectors:
E-107, E-108
ACTUATOR TEST REFERENCE TABLE
The MUT-II activates 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.Inspection itemDrive contents
01HBB pump motorOperate the pump motor for one second.
02HBB buzzerSound the buzzer for three seconds.


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35B-1
ANTI-SKID
BRAKING SYSTEM
(ABS) <4WD>
CONTENTS
GENERAL INFORMATION 2..................
SERVICE SPECIFICATIONS 4.................
LUBRICANT Refer to GROUP 35A...........
SEALANTS Refer to GROUP 35A............
SPECIAL TOOLS 4..........................
TROUBLESHOOTING 4.......................
ON-VEHICLE SERVICE 27...................
Wheel Speed Sensor Output Voltage
Measurement 27...............................
ABS Valve Relay Continuity Check 28...........
Hydraulic Brake Booster (HBB) - Hydraulic Unit
Check 29......................................
Solenoid Valve Check 30.......................
When the Battery is Flat 31....................
Brake Pedal Check and Adjustment
Refer to GROUP 35A ..........................
Hydraulic Brake Booster (HBB) Operation Check
Refer to GROUP 35A ..........................
Hydraulic Brake Booster (HBB) Check
Refer to GROUP 35A ..........................Motor Relay Continuity Check
Refer to GROUP 35A ..........................
Bleeding Refer to GROUP 35A..................
Brake Fluid Level Sensor Check
Refer to GROUP 35A ..........................
Disc Brake Pad Check and Replacement
Refer to GROUP 35A ..........................
Brake Disc Thickness Check
Refer to GROUP 35A ..........................
Brake Disc Runout Check and Correction
Refer to GROUP 35A ..........................BRAKE PEDAL Refer to GROUP 35A........
HYDRAULIC BRAKE BOOSTER (HBB)
Refer to GROUP 35A ........................
HBB BUZZER Refer to GROUP 35A..........
FRONT DISC BRAKE Refer to GROUP 35A..
REAR DISC BRAKE Refer to GROUP 35A....
ABS-ECU 32................................
WHEEL SPEED SENSOR 33.................
G-SENSOR 36..............................


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ABS <4WD> -Troubleshooting35B-7
INSPECTION CHART FOR DIAGNOSIS CODES
Diagnosis code
No.Diagnosis itemReference page
11Wheel speed sensor (FR) system (open circuit or short - circuit)35B-8
12Wheel speed sensor (FL) system (open circuit or short - circuit)35B-8
13Wheel speed sensor (RR) system (open circuit or short - circuit)35B-8
14Wheel speed sensor (RL) system (open circuit or short - circuit)35B-8
15Wheel speed sensor system (output signal abnormality)35B-9
16ABS-ECU or valve relay power supply system (abnormal voltage
drop or rise)35B-10
21Wheel speed sensor (FR) system35B-8
22Wheel speed sensor (FL) system35B-8
23Wheel speed sensor (RR) system35B-8
24Wheel speed sensor (RL) system35B-8
26Center differential lock switch system35B-11, 12
27Rear differential lock switch system35B-11, 12
32G sensor system35B-13
33Stop lamp switch system35B-14
41Control solenoid valve (FR)
systemIf there is no response to the
solenoid valve drive signal35B-15
42Control solenoid valve (FL)
systemcorresponding to each respec-
tive item
43Control solenoid valve (RR)
system
44Control solenoid valve (RL)
system
45Changeover solenoid valve
(FR) system
46Changeover solenoid valve
(FL) system
51Valve relay system (ON problem)35B-16
52Valve relay system(OFFproblem)35B-17
55HBB systemCarry out HBB troubleshoot-
ing. (Refer to GROUP 35A.)
63ABS-ECU system35B-32 (ABS-ECU replace-
ment)
NOTE
*: Code No.16 is erased from the memory if the condition returns to normal.


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ABS <4WD> -TroubleshootingABS <4WD> -Troubleshooting35B-8
INSPECTION PROCEDURE CLASSIFIED BY DIAGNOSIS CODE
Code No. 11, 12, 13, 14 Wheel speed sensor system
(open circuit or short-circuit)Probable cause
Code No. 21, 22, 23, 24 Wheel speed sensor system
Code Nos. 11, 12, 13, 14 are output when theopencircuit or short-circuit
detection carried out by the ABS-ECU hardware circuit detects that there is an
opencircuit or short-circuit in the (+) or ( - ) wire in one of the four wheel speed
sensors and signals are consequently notbeing input.DMalfunction of wheel speed sensor
DMalfunction of harness or connector
DMalfunction of the ABS-ECU
Code No. 21, 22, 23, 24 are output at the following times:
DIf an opencircuit cannot be verified, but one or more of the wheel speed
sensors does not output any signal when the vehicle speed is a certain
number of km/h or higher.
DWhen a problem such as chipped orplugged - uprotor tooth is detected, or if
the sensor output drops and anti - skid control is continuously carried out due
to a malfunctioning sensor or a warped ABS rotor.DMalfunction of wheel speed sensor
DMalfunction of harness or connector
DMalfunction of ABS rotor
DExcessive clearancebetween sensor and ABS
rotor
DMalfunction of the ABS-ECU
DMalfunction of wheel bearing
NG
NG
Replace the ABS-ECU.
NG
Repair
OK
Check the trouble symptoms.
OK
Check the following connector:E-106
OK
Wheel bearing check
(Refer to GROUP 26, 27 -
On-vehicle Service.)
NG
Replace
OK
ABS rotor check
(Refer to P.35B-33.)
NG
Replace
Wheel speed sensor check
(Refer to P.35B-34.)
OK
Wheel speed sensor output voltage check (Refer to P.35B-27.)
OK
Check the following connectors:A-04 , A-23, A-39,
D-124, D-143 , E-10, E-106, F-17, G-11, G-15
Wheel speed sensor installation checkNG
Repair
OK
Measure at ABS-ECU connector E-106.
DDisconnect the connector and measure at the harness
side.
DFront: resistance between 10 – 23, 7 – 20
Rear: resistance between 8 – 21, 9 – 22
OK:1.0 - 1.5 k
WNG
NG
Replace
NG
Repair
OK
Check the trouble
symptoms.
NG
Check the harness wire, and repair if necessary.
DBetween each wheel speed sensor and ABS-ECU
Wheel speed sensor check (Refer to P.35B-34.)


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ABS <4WD> -Troubleshooting35B-9
Code No. 15 Wheel speed sensor system (output signal
abnormality)Probable cause
This malfunction code is output when any one of the wheel speed sensor output
signals during driving is abnormal (exceptopen andshort circuit).DUneven tyre size for all four wheels
DIncorrect wheel speed sensor installation
DMalfunction of wheel speed sensor
DMalfunction of harness or connector
DMalfunction of ABS rotor
DMalfunction of wheel bearing
DMalfunction of the ABS-ECU
NG
Check the harness wire, and repair if necessary.
DBetween each wheel speed sensor and ABS-ECU
OK
Wheel bearing check
(Refer to GROUP 26, 27 - On-vehicles Service.
NG
Replace
OKNG
Replace
NG
Replace the ABS - ECU.
OK
Check the trouble
symptoms.
NG
Repair
OK
Check the following connector:E-106
OK
Wheel speed sensor output voltage check (Refer to P.35B-27.)NGWheel speed sensor check (Refer to P.35B-34.)
NG
Wheel speed sensor installation checkNG
Repair
Are the tyres on all four wheels of identical size?NOFit tyres which are of identical size.
YES
Check the trouble symptoms.
Check the ABS rotor (Refer to P.35B-33).


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ABS <4WD> -Troubleshooting35B-10
Code No.16 ABS-ECU power supply system (abnormal
voltage increase or decrease)Probable cause
This code is output if the ABS-ECU power supply voltage or valve relay power
supply voltage drops below or rises above a certain level.DMalfunction of battery
DMalfunction of harness or connector
DMalfunction of the ABS-ECU
Caution
If the system voltage drops or rises during inspection, this code will beoutput to indicate a current
problem. And correct problem diagnosis will not be possible. Before carrying out the following
procedure, check the battery and recharge it if necessary.
OKNG
Repair
OK
(1)NGCheck the following connectors:D-32 , D-128,
D-208, D-210 , D-213 , E-08 , E-13,
E-106
NG
Check the harness wire, and repair if necessary.
DBetween the ignition switch and the ABS-ECU (2)NG
OK
Check the trouble symptoms.
NG
Repair
NG
Check the harness wire, and repair if necessary.
DBetween the ignition switch and the ABS-ECU
Check the following connectors:E-13, E-107
Measure at E-106, E-107 ABS-ECU connectors.
DDisconnect the connector and measure at the harness
side.
DIgnition switch: ON
(1) Voltage between terminal 13 and body earth
OK:System voltage
(2) Voltage between terminal 31 and body earth
OK:System voltage
NG (1)NG
Check the ABS valve relay (Refer to P.35B-28).NGReplace the ABS valve relay.
OK
Check the harness wire, and repair if necessary.
DBetween ignition switch and ABS valve relay
OK
Repair
OK
Replace the ABS-ECU.
Check the trouble symptoms.
Check the following connectors:B-21X, D-32 ,
D-128, D-208, D-210 , D-213 , E-13 OK
NG(2)NG
Check the harness wire, and repair if necessary.
DBetween fusible link No. 8 and the ABS valve relay
OK
NG
Repair
NGCheck the trouble symptoms.
Check the following connector:B-21X
OK
NG
OK
NG
Repair
Check the harness wire, and repair if necessary.
DBetween ABS-ECU and ABS valve relayNG
Check the trouble symptoms.
Check the following connectors:E-107, B-21X
OK
OK
NG
RepairCheck the trouble symptoms.
Check the following connectors:B-17, B-18, B-21X, E-107
NG
Repair
Check the harness wire, and repair if necessary.
DBetween ABS valve relay and HBB and ABS-ECU terminal
(48)
Measure at ABS-ECU connector E-107.
DDisconnect the connector and measure at the harness
side.
DIgnition switch: ON
DVoltage between terminal 37 and body earth
OK:System voltage
Measure at ABS valve relay connector B-21X.
DDisconnect the connector and measure at the harness
side.
DIgnition switch: ON
(1) Voltage between 1 and body earth
OK:System voltage
(2) Voltage between terminal 5 and body earth
OK:System voltage
Check the trouble symptoms.


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