Mitsubishi 380. Manual - part 957

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-53

STEP 4. Check ABS-ECU connector A-02 for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.
Q: Is ABS-ECU connector A-02 damaged?

YES : Repair or replace the damaged component(s). Refer 

to GROUP 00E, Harness Connector Inspection 

P.00E-2

. Then go to Step 8.

NO :  An open or short circuit may be present in the 

solenoid valve power supply circuit. Repair the wiring 
harness between ABS-ECU connector A-02 terminal 
2 and fusible link No.3.Then go to Step 8.

FUSIBLE LINK No.3
ABS (motor supply)  
       (30 A) 

RELAY BOX

35DB097A

16DB402A

A-02 (GR)

CONNECTOR: A-02 

A-02 HARNESS CONNECTOR:

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-54

STEP 5. Measure the resistance at ABS-ECU connector 
A-02.
(1) Disconnect the connector A-02, and use special tool 

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

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.

(2) Measure the resistance between terminal 4 and ground. It 

should be 2 ohms or less.

Q: Is the measured resistance 2 ohms or less?

YES : Go to Step 7.
NO :  Go to Step 6.

STEP 6. Check ABS-ECU connector A-02 for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.
Q: Is ABS-ECU connector A-02 damaged?

YES : Repair or replace the damaged component(s). Refer 

to GROUP 00E, Harness Connector Inspection 

P.00E-2

. Then go to Step 8.

NO :  An open circuit may be present in the ground circuit. 

Repair the wiring harness between ABS-ECU 
connector A-02 terminal 4 and the body ground. Then 
go to Step 8.

35DB098A

CONNECTOR: A-02

HYDRAULIC UNIT

(WITH BUILT-IN ABS-ECU)

TEST 

HARNESS

(MB991219)

16DB402A

A-02 (GR)

CONNECTOR: A-02 

A-02 HARNESS CONNECTOR:

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-55

STEP 7. 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 C1266, C1273 or C1274 set?

YES : Replace the hydraulic unit (integrated with 

ABS-ECU). Then go to Step 8.

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

.

STEP 8. 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 C1266, C1273 or C1274 set?

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

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-56

DTC C1276/ C1278/ C1279 Valve Relay System

CAUTION

If there is any problem in the CAN bus lines, an 
incorrect diagnostic trouble code may be set. 
Prior to this diagnosis, diagnose the CAN bus 
lines.

NOTE: If the ABS-8 ECU or the active wheel 
speed sensor are disconnected, or if the wiring is 
an open/ short circuit, the ABS 8 ECU will shut 
off power supply to the respective wheel speed 
sensor. All other wheel speed sensors will oper-
ate normally. To restore the power supply, the 
ignition switch must be turned to the "OFF" posi-
tion then to the "ON" position again.

.

CIRCUIT OPERATION

• The ABS-ECU contains the power supply circuit 

(terminal 3) for the solenoid valve. The solenoid 
valve is energized by a MOSFET driver, which is 
integrated in the ABS-ECU.

• A MOSFET driver, which is integrated in the 

ABS-ECU, is always energizing the solenoid 
valve unless the initial check is in progress when 
the ignition switch is turned on.

.

ABS DTC SET CONDITIONS

These diagnostic trouble codes will be set under the 
cases below.

DTC C1278 (Valve relay OFF failure)

• After the ABS-ECU turned on the MOSFET 

driver, the solenoid valve is not energized (valve 
relay OFF failure).

DTC C1278 (Valve relay ON failure)

• After the ABS-ECU turned off the MOSFET 

driver, the solenoid valve still remains energized 
(valve relay ON failure).

.

35DB090A

A

FUSIBLE LINK
ABS (solenoid valve)  
       (20 A) 

RELAY BOX

35DB093A