Mitsubishi Montero (2004+). Manual - part 737

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-205

ETACS-
ECU

JUNCTION
BLOCK

BATTERY

FRONT 
DOOR 
SWITCH

(RH)

REAR 
DOOR 
SWITCH

(RH)

FRONT 
DOOR 
SWITCH

(LH)

REAR 
DOOR 
SWITCH

(LH)

REAR 
PERSONAL
LIGHT

(LH)     (RH)

CARGO
SPACE
LIGHT

CONTROL CIRCUIT 

TRANSMITTER 

THEFT-ALARM
HORN RELAY 

THEFT-ALARM
HORN 

RELAY
BOX 

RELAY
BOX 

DOME
LIGHT

BACK
DOOR 
SWITCH

FRONT TURN
SIGNAL LIGHT (LH)

FRONT TURN
SIGNAL LIGHT (RH)

REAR COMBINATION LIGHT
(TURN SIGNAL LIGHT) (RH)

REAR COMBINATION LIGHT
(TURN SIGNAL LIGHT) (LH)

FUSIBLE LINK 

1

COMBINATION
METER

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-206

INSPECTION PROCEDURE E-1: Keyless Entry System: Keyless entry system does not operate.

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
A receiver is incorporated in the ETACS-ECU. This 
receiver receives a lock or unlock signal from the 
transmitter.

.

TROUBLESHOOTING HINTS

• The transmitter may be defective

• The ETACS-ECU may be defective

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

Transmitter ("LOCK"/"UNLOCK") Input Signal

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-207

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 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 according to the procedure 

below to display "ECU COMM CHK."

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

(5) Scan tool MB991958 should show "OK" on the "ECU 

COMM CHK" menu for 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

."

STEP 2. Check the input signal (by using the pulse check 
mode of the monitor.)
Check the input signals from the transmitter.
(1) Connect the special tool. Refer to "How to connect SWS 

monitor 

P.54B-7

(2) Operate scan tool MB991958 as follows:

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

(3) Push the transmitter "LOCK" or "UNLOCK" switch.
(4) Check that scan tool MB991958 sounds.
Q: When the transmitter "LOCK" or "UNLOCK" switch is 

pushed, does scan tool MB991958 sound?
YES : Replace the ETACS-ECU. Verify that all the doors 

can be locked or unlocked by using the transmitter. 

NO :  Refer to Inspection Procedure P-10 "The 

ETACS-ECU does not receive a signal from the lock, 
unlock switch or panic switch 

P.54B-626

".

AC309091

MB991911

MB991827

MB991824 

AB

MB991806

MB991862

DATA LINK
CONNECTOR 
(16-PIN)

DATA LINK
CONNECTOR 
(13-PIN)

AC307591 AB

MB991911

DATA LINK

CONNECTOR

MB991824

MB991827

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-208

INSPECTION PROCEDURE E-2: Keyless Entry System: The dome light, hazard warning lights 
(turn-signal lights) and horn do not operate through the answerback function.

.

CIRCUIT OPERATION
The ETACS-ECU operates the following functions 
when it receives a lock or unlock signal from the 
transmitter:

• Dome light answerback function

• Hazard warning lights answerback function

• Horn answerback function

.

TECHNICAL DESCRIPTION (COMMENT)
The hazard warning lights or horn answerback func-
tions can be disabled. However, the dome light 
answerback function can be disabled.

.

TROUBLESHOOTING HINTS

• The hazard warning lights (turn-signal lights) may 

be defective

• The horn may be defective

• The dome light may be defective

• The ETACS-ECU may be defective

• The wiring harness may be damaged or the con-

nector(s) may have loose, corroded or damaged 
terminals, or terminals pushed back in the con-
nector

DIAGNOSIS

STEP 1. Verify the keyless entry system.
Q: Does the keyless entry system work normally?

YES : Go to Step 2.
NO :  Refer to Inspection Procedure E-1 "Keyless entry 

system does not work 

P.54B-206

."

STEP 2. Verify the answerback adjustment function.
Check the answerback functions. (Refer to GROUP 42, Key-
less Entry System 

− On-vehicle Service − Enabling/disabling 

the Answerback Function 

P.42-58

.)

Q: Does the answerback function work normally?

YES : No action is necessary and testing is complete.
NO :  Go to Step 3.

STEP 3. Verify the trouble symptom.
Q: Which answerback function is defective?

Only the dome light  : Go to Step 4.
Only the hazard warning lights (turn-signal lights) : Go 

to Step 5.

All functions do not work [dome light, hazard warning 
lights (turn-signal lights) and horn]. : Replace the 

ETACS-ECU. Verify that the answerback functions 
work normally.

STEP 4. Verify the dome light.
Q: Does the dome light illuminate normally?

YES : Replace the ETACS-ECU. Verify that the answerback 

functions work normally.

NO :  Refer to Inspection Procedure M-1 "The dome light do 

not illuminate or go out normally."

P.54B-428