Mitsubishi 380. Manual — part 964

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-81

INSPECTION PROCEDURE 5: Faulty ABS Operation

.

TECHNICAL DESCRIPTION (COMMENT)

The cause depends on driving and road surface con-
ditions, so diagnosis may be difficult. However, if no
diagnostic trouble code is displayed, carry out the fol-
lowing inspection.

.

TROUBLESHOOTING HINTS (The most
likely causes for this case:)

• Malfunction of the hydraulic unit

Circuit drawings

• Refer to circuit diagrams GROUP-

90

• Refer to configuration diagrams GROUP-

80

.

DIAGNOSIS

STEP 1. Hydraulic unit check
Refer to

P.35B-90

.

Q: Is the hydraulic unit normal?

YES : Go to Step 2.
NO : Connect the brake pipes correctly, repair the external

brake lines, or replace the hydraulic unit.

STEP 2. Verify that the condition described by the
customer exists.

Q: Can any faults be found with the brake operation?

YES : Check the brake system related components except

the ABS system.

NO : The procedure is complete.

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-82

DATA LIST REFERENCE TABLE

M1352011500780

The following items can be read by the diagnostic
tool from the ABS-ECU input data.

MUT-III
DIAGNOSTI
C TOOL
DISPLAY

DATA
LIST
ITEM
NO.

CHECK ITEM

CHECKING REQUIREMENTS

NORMAL
VALUE

FL wheel
speed sensor

01

Front-left wheel speed sensor

Drive the vehicle

Vehicle speeds
displayed on the
speedometer
and diagnostic
tool are identical.

FR wheel
speed sensor

02

Front-right wheel speed sensor

RL wheel
speed sensor

03

Rear-left wheel speed sensor

RR wheel
speed sensor

04

Rear-right wheel speed sensor

Power supply
voltage

05

ABS-ECU power supply voltage Ignition switch power supply

voltage and valve monitor
voltage

Battery positive
voltage

Stop lamp
switch (input)

06

Stoplamp switch

Depress the brake pedal.

ON

Release the brake pedal.

OFF

Stop lamp
switch

13

Stoplamp switch

Depress the brake pedal.

ON

Release the brake pedal.

OFF

Pump motor

21

Pump motor

When the ABS outputs the
operation permission signal
during driving

ON

When the ABS outputs the
operation permission signal
during driving

OFF

Valve relay

30

Valve relay

When the ABS outputs the
operation permission signal
during driving

ON

When the ABS outputs the
operation permission signal
during driving

OFF

TCL mode

35

TCL operation

When the TCL outputs the
operation permission signal
during driving

ON

When the TCL outputs the
operation inhibition signal
during driving

OFF

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-83

ACTUATOR TEST REFERENCE TABLE

M1352011600765

The diagnostic tool activates the following actuators
for testing.

NOTE: If the ABS-ECU runs down, actuator testing
cannot be carried out.

NOTE: Actuator testing is only possible when the
vehicle is stationary.

.

ACTUATOR TEST SPECIFICATIONS

NO.

ITEM

PARTS TO BE
ACTIVATED

01

FL wheel speed sensor

Solenoid valves and
pump motors in the
hydraulic unit (simple
inspection mode)

02

FR wheel speed sensor

03

RL wheel speed sensor

04

RR wheel speed sensor

09

Engine TCL Drive

Outputs the engine
torque control signal
(engine torque = 0) to
Engine ECU for three
seconds.

AC100172AI

ACTIVATION PATTERN

A
B
C

SOLENOID

VALVE

END OF

FORCED

ACTION

START OF

FORCED

ACTION

1 s

2 s

PUMP

MOTOR

ON

OFF

NOTE

A:

B:

C:

HYDRAULIC PRESSURE INCREASES

HYDRAULIC PRESSURE HOLDS

HYDRAULIC PRESSURE DECREASES

APPROXIMATELY

0.05 s

APPROXIMATELY

0.01 s

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-84

CHECK AT ABS-ECU

M1352011800769

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TERMINAL VOLTAGE CHECK CHART

Required Special Tool:
MB991219: Inspection Test Harness
1. Disconnect the ABS-ECU connector A-02, and use special

tool Inspection Test Harness (MB991219) to probe the
wiring harness-side connector.

2. Measure the voltages between ground and each terminal

listed below in the table. Also measure voltages between
ground and each terminal listed below in the table.

NOTE: The special tool (Inspection test harness) MB991219
for connector pin contact pressure should be used. The test
probe should never be forcibly inserted, as it may cause a
defective contact.

3. The terminal layouts are shown in the illustrations below.

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CONNECTOR
TERMINAL NO

SIGNAL

CHECKING REQUIREMENT

NORMAL
CONDITION

3

Solenoid valve power
supply

Always

Battery positive
voltage

20

Stop light switch input Ignition

switch: "ON"

Stop light switch: "ON"

Battery positive
voltage

Stop light switch: "OFF"

Approximately 0 V

2

Motor power supply

Always

Battery positive
voltage

18

ABS-ECU power
supply

Ignition switch: "ON"

Battery positive
voltage

Ignition switch: "START"

Approximately 0 V