Mitsubishi Montero (2004+). Manual - part 720

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-137

INSPECTION PROCEDURE C-5: Central Door Locking System: All the doors do not lock with just the 
driver's inside lock knob operation.

.

TECHNICAL DESCRIPTION
The driver's door lock actuator switch or the 
ETACS-ECU may be defective.

.

TROUBLESHOOTING HINTS

• The driver's door lock actuator switch may be 

defective

• The ETACS-ECU may be defective

• The wiring harness or connectors may have 

loose, corroded or damaged terminals, or termi-
nals pushed back in the connector

DIAGNOSIS

Required Special Tools:

• MB991223: Harness Set

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

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

• MB991827: MUT-III USB Cable

• MB991911: MUT-III Main Harness B

Central Door Lock (Door Lock Actuator Switch) Circuit

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-138

Check the input signal (by using the pulse check mode of 
the monitor.)
Check the input signals from the driver's door lock actuator 
switch.

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 MB991502 to the data link connector 

(16-pin).

(2) Operate scan tool MB991958 as follows:

1. Select "SYSTEM SELECT."
2. Select "SWS."
3. Select "PULSE CHECK."

(3) Lock or unlock the driver's inside lock knob.
(4) Check scan tool MB991958 sounds or not.
Q: Does scan tool MB991958 sound when the driver's 

inside lock knob is locked or unlocked, or the 
passenger's side lock knob is moved from the lock to 
the unlock position?
YES : Replace the ETACS-ECU. Verify that all the doors 

can be locked or unlocked by operating the driver's 
inside lock knob.

NO :  Refer to Inspection Procedure O-6 "ETACS-ECU 

does not receive a signal from the driver's door lock 
actuator switch 

P.54B-527

."

AC307591 AB

MB991911

DATA LINK

CONNECTOR

MB991824

MB991827

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-139

INSPECTION PROCEDURE C-6: Central Door Locking System: Forgotten key prevention function 
does not work normally.

NOTE: This troubleshooting procedure requires the 
use of scan tool MB991958 and SWS monitor kit 
MB991862. For details on how to use the SWS mon-
itor, refer to "How to use SWS monitor 

P.54B-10

."

.

CIRCUIT OPERATION
The ETACS-ECU operates the forgotten key preven-
tion function according to the following switches:

• Key reminder switch: OFF

• Driver's or front passenger's door switch: ON

• Driver's door lock actuator switch: being turned 

ON

The ETACS-ECU activates the forgotten key preven-
tion function under the following conditions:

• Ignition key: inserted into the ignition key cylinder

• Driver's or front passenger's door: open

• Driver’s or front passenger’s door lock: being 

locked electrically

• Driver’s door lock: being locked manually

.

TECHNICAL DESCRIPTION (COMMENT)
 If the forgotten key prevention function does not 
work normally, the input circuit from the switches or 
the ETACS-ECU may be defective.

.

TROUBLESHOOTING HINTS

• The key reminder switch may be defective

• The driver's or front passenger's door switch may 

be defective

• The driver's door lock actuator switch may be 

defective

• The ETACS-ECU may be defective

• The wiring harness or connectors may have 

loose, corroded or damaged terminals, or termi-
nals pushed back in the connector

Forgotten Key Prevention Circuit

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-140

DIAGNOSIS

Required Special Tools:

• MB991223: Harness Set

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

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

• MB991827: MUT-III USB Cable

• MB991911: MUT-III Main Harness B

• MB991813: SWS Monitor Kit

• MB991806: SWS Monitor Cartridge

• MB991812: SWS Monitor Harness (For Column-ECU)

• MB991822: Probe Harness

STEP 1. Use scan tool MB991958 to select "ECU COMM 
CHK" on the SWS monitor display.
Check the ETACS-ECU.

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 the special tool. Refer to "How to connect SWS 

monitor 

P.54B-7

(2) Connect the SWS monitor kit MB991862 to the data link 

connector (13-pin).

(3) Turn the ignition switch to the "LOCK" (OFF) position.
(4) Operate scan tool MB991958 as follows:

1. Select "SYSTEM SELECT."
2. Select "SWS."
3. Select "SWS MONITOR."
4. Select "ECU COMM CHK".

(5) Check scan tool MB991958 should show "OK" on the 

"ETACS ECU" menu.

Q: Is "OK" displayed on the "ETACS ECU" menu?

YES : Go to Step 2.
NO :  Refer to Inspection Procedure A-3 "Communication 

with ETACS-ECU is not possible 

P.54B-42

."

AC309091

MB991911

MB991827

MB991824 

AB

MB991806

MB991862

DATA LINK
CONNECTOR 
(16-PIN)

DATA LINK
CONNECTOR 
(13-PIN)