Mitsubishi Galant 9G. Manual — part 1624

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-80

STEP 1. Using scan tool MB991958, diagnose the CAN bus
line.

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?

YES : Go to Step 2.
NO : Repair the CAN bus line (Refer to GROUP 54C,

Diagnosis

P.54C-14

). Then go to Step 2.

STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Turn the ignition switch to the "ON" position.
(2) Erase the DTC.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
(4) Turn the ignition switch to the "ON" position.
(5) Check if the DTC is set.
(6) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC U1073 set?

YES : Replace the ABS-ECU. Then go to Step 3.
NO : It can be assumed that this malfunction is intermittent.

Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points

− How to

Cope with Intermittent Malfunction

P.00-14

.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-81

STEP 3. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Turn the ignition switch to the "ON" position.
(2) Erase the DTC.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
(4) Turn the ignition switch to the "ON" position.
(5) Check if the DTC is set.
(6) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC U1073 set?

YES : Go to Step 1.
NO : The procedure is complete.

SYMPTOM CHART

M1352011400619

CAUTION

During diagnosis, a DTC code associated with
another system may be set when the ignition
switch is turned on with connector(s) discon-
nected. On completion, confirm all systems for
DTC code(s). If DTC code(s) are set, erase them
all.
NOTE: If steering movements are made when driv-
ing at high speed, or when driving on road surfaces
with low frictional resistance, or when passing over
bumps, the ABS may operate although sudden brak-
ing is not being applied. Because of this, when get-
ting information from the customer, check if the
problem occurred while driving under such condi-
tions as these.

NOTE: During ABS operation, the brake pedal may
vibrate a little or may not be able to be pressed. Such
conditions are due to intermittent changes in hydrau-
lic pressure inside the brake line to prevent the
wheels from locking. This is normal.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SYMPTOMS

INSPECTION
PROCEDURE NO.

REFERENCE PAGE

Communication between the scan tool and the
ABS-ECU is not possible.

1

P.35B-82

Power supply circuit system

2

P.35B-84

When the ignition key is turned to "ON" (Engine
stopped), the ABS warning light does not illuminate.

3

P.35B-90

The ABS warning light remains illuminated after the
engine is started.

4

P.35B-90

Faulty ABS operation

5

P.35B-93

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-82

SYMPTOM PROCEDURES

INSPECTION PROCEDURE 1: Communication between Scan Tool and the ABS-ECU is not possible.

ABS-ECU

IGNITION
SWITCH (IG1)

DATA LINK
CONNECTOR

JUNCTION
BLOCK

JOINT
CONNECTOR (3)

POWER
SUPPLY

Data Link Connector Circuit

AC304742

A-02 (GR)

CONNECTOR: A-02

HYDRAULIC UNIT
(WITH BUILT-IN ABS-ECU)

AC

AC305231

CONNECTORS : C-02, C-29

C-29

BX

C-02

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-83

.

TECHNICAL DESCRIPTION (COMMENT)

If the scan tool (MUT-III Sub Assembly) cannot com-
municate with the ABS system, the CAN bus lines
may be defective. If the ABS system does not work,
the ABS-ECU or its power supply circuit may be
defective.

.

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

• Damaged wiring harness or connector

• Malfunction of the hydraulic unit (Integrated with

ABS-ECU)

.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A

STEP 1. Using scan tool MB991958, diagnose the CAN bus
line.

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
Use scan tool MB991958 to diagnose the CAN bus lines.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
Q: Is the check result satisfactory?

YES : Check and repair the power supply circuit system

(Refer to

P.35B-84

).

NO : Repair the CAN bus lines (Refer to GROUP 54C,

Diagnosis-CAN Bus Diagnostic Chart

P.54C-14

).

AC305028

ACCELERATOR
PEDAL

AC

CONNECTOR: C-125

C-125(B)

AC305415

CONNECTORS : C-214, C-215

C-214

C-215

AW

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827