Mitsubishi Montero (2002-2004). Manual - part 1054

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-87

STEP 4. Check the wiring harnesses between M-ASTC-ECU 
connectors E-119 terminals 4, 22 and ground as well as between 
M-ASTC-ECU connectors E-120 terminals 56, 64 and ground.
NOTE: After inspecting M-ASTC-ECU connectors E-119 and E-120, 
inspect the wire. If M-ASTC-ECU connectors E-119 and E-120 are 
damaged, repair or replace them. Refer to GROUP 00E, Harness 
Connector Inspection 

P.00E-2

. If the connector has been repaired or 

replaced, go to Step 5.
Q: Are the wiring harnesses between M-ASTC-ECU connectors 

E-119 terminals 4, 22 and ground as well as between M-ASTC-
ECU connectors E-120 terminals 56, 64 and ground 
damaged?
YES :  Repair them and then go to Step 5.
NO :  Replace the M-ASTC-ECU and go to Step 5.

STEP 5. Retest the system
Q: Does the scan tool communicate with the ABS system?

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

AC203901

AC204627AO

E-119

CONNECTORS: E-119, E-120

E-119

HARNESS CONNECTOR:
COMPONENT SIDE

E-120

HARNESS CONNECTOR:
COMPONENT SIDE

E-120

AC204710 AB

GROUND POINT

ACX01508

GROUND POINT

AF

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-88

INSPECTION PROCEDURE 2: When the Ignition Switch is Turned the "ON" Position (Engine Stopped 
or after Start-up), the ABS Warning Light does not Illuminate.

AC204874 AB

ABS Warning Light Circuit

AC204674

AB

B-21X (VALVE RELAY)

CONNECTOR: B-21X

AC204547AC

CONNECTORS: D-208, D-210

D-208

D-210

JUNCTION BLOCK
(FRONT VIEW)

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-89

.

CIRCUIT OPERATION

• The ABS warning light power is supplied from the 

ignition switch. The M-ASTC-ECU grounds the 
circuit to illuminate the light. The light also illumi-
nates when the valve relay is switched to OFF.

• The M-ASTC-ECU illuminates the ABS warning 

light for 3 seconds while running self-check. This 
light can be illuminated for 3 seconds upon start-
up or ignition switch to the "ON" position, engine 
stopped. The M-ASTC-ECU drives the valve 
relay in the order of OFF to ON to OFF to ON dur-
ing initial check to check the valve relay.

.

TECHNICAL DESCRIPTION (COMMENT)
When the M-ASTC-ECU warning light circuit is in 
good condition, the ABS warning light illuminates for 
3 seconds when the ignition switch is turned to the 
"ON" position. For instance, if the ABS warning light 
circuit of M-ASTC-ECU is out of order, the light illumi-

nates once when the valve relay is switched to the 
"OFF" position during initial check. If the ABS warn-
ing light does not illuminate when the ignition switch 
is turned to the "ON" position, the following items are 
suspected to be the cause: open circuit on the light 
power circuit, burned out light bulb, open circuit 
between the ABS warning light and the M-ASTC-
ECU, and open circuit between the ABS warning 
light and the valve relay.

.

TROUBLESHOOTING HINTS

• Damaged wiring harness or connector

• Burnt out ABS warning light bulb

• Malfunction of the M-ASTC-ECU

.

AC204546 AB

CONNECTOR: D-03

D-03 (GR)

AC203901AF

CONNECTOR: E-120

E-120

AC204385

CONNECTORS: E-108, E-110

AE

E-110

E-108(B)

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-90

DIAGNOSIS

Required Special Tool:

• MB991223: Harness Set

STEP 1. Check the illumination of brake warning light.
Turn the ignition switch to the "ON" position. The brake warning 
light should turn on.
Q: Does the brake warning light turn on? 

YES : Go to Step 2.
NO :  Go to Step 7.

STEP 2 Check the ABS warning light bulb.
(1) Remove the combination meter (Refer to GROUP 54A, 

Combination Meter 

P.54A-65

).

(2) Check the ABS warning light bulb.
Q: Is the bulb burned out?

YES : Replace the bulb and then go to Step 10.
NO :  Go to Step 3.

STEP 3. Check the ABS warning light circuit at M-ASTC-
ECU connector E-120.
(1) Disconnect M-ASTC-ECU connector E-120 and measure at 

the harness side.

(2) Ground the terminal 62.
(3) Turn the ignition switch to the "ON" position. The ABS 

warning light should turn on.

Q: Is the ABS warning light turn on?

YES : Replace the M-ASTC-ECU and then go to Step 5.
NO :  Go to Step 4.

AC203901

AC204627

CONNECTOR: E-120

AS

E-120

HARNESS CONNECTOR:
COMPONENT SIDE