Mitsubishi Montero (2004+). Manual - part 807

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-485

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CIRCUIT OPERATION
When the theft-alarm system is triggered, the 
ETACS-ECU sounds the theft-alarm horn and all the 
vehicle horns.

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TECHNICAL DESCRIPTION (COMMENT)
If the theft-alarm horn and the vehicle horns do not 
sound when the theft-alarm system is triggered, the 
ETACS-ECU may be defective.

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TROUBLESHOOTING HINTS

• The theft-alarm horn may be defective

• The horn may be defective

• The theft-alarm horn relay may be defective

• The horn relay 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 Tool:

• MB991223: Harness Set

AC204167

CONNECTORS : A-04, A-17

A-17

AS

A-04(B)

AC204183

CONNECTORS : A-10X, A-11X

A-11X

A-10X

AK

AC204166

CONNECTORS : A-27, A-28

AJ

A-28(B)

A-27(B)

AC204170

CONNECTORS : D-27, D-28

BQ

D-28

D-27

AC204174

CONNECTOR : D-223

D-223(B)

AF

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-486

STEP 1. Check which horn is defective.
Check which horn does not sound when the theft-alarm system 
is triggered.
Q: Which horn does not sound?

Theft-alarm horn : Go to Step 2.
Horns (high and low)  : Go to Step 12.
Horn (high or low)  : Go to Step 20.
Theft-alarm horn and all vehicle horns : Replace the 

ETACS-ECU. All the vehicle horn (including the 
theft-alarm horn) should sound when the theft-alarm 
system is triggered.

STEP 2. Check the theft-alarm horn.
Connect the battery as shown, and check that the theft-alarm 
horn sounds.
Q: Does the theft-alarm horn sound?

YES : Go to Step 3.
NO :  Replace the theft-alarm horn. All the vehicle horn 

(including the theft-alarm horn) should sound when 
the theft-alarm system is triggered.

STEP 3. Check theft-alarm horn relay connector A-11X for 
loose, corroded or damaged terminals, or terminals 
pushed back in the connector.
Q: Is theft-alarm horn relay connector A-11X in good 

condition?
YES : Go to Step 4.
NO :  Repair or replace the damaged component(s). Refer 

to GROUP 00E, Harness Connector Inspection 

P.00E-2

. All the vehicle horn (including the theft-alarm 

horn) should sound when the theft-alarm system is 
triggered.

ACX02352

AC204183

CONNECTOR : A-11X

RELAY BOX SIDE

AE

2 1

5

4

3

A-11X

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-487

STEP 4. Check the theft-alarm horn relay.

Q: Is the theft-alarm horn relay normal?

YES : Go to Step 5.
NO :  Replace the theft-alarm horn relay. All the vehicle 

horn (including the theft-alarm horn) should sound 
when the theft-alarm system is triggered.

STEP 5. Check the fusible link (1) line of the power supply 
circuit to the theft-alarm horn relay. Test at theft-alarm horn 
relay connector A-11X.
(1) Disconnect theft-alarm horn relay connector A-11X and 

measure the voltage available at the relay box side of the 
connector.

(2) Measure the voltage between terminal 3 and ground, and 

also between terminal 5 and ground.

• The voltage should be approximately 12 volts (battery 

positive voltage).

Q: Is the measured voltage approximately 12 volts (battery 

positive voltage)?
YES : Go to Step 7.
NO :  Go to Step 6.

BATTERY 
VOLTAGE

TESTER 
CONNECTION

SPECIFIED 
CONDITION

Not applied

4 

− 5

Open circuit

1 

− Battery (−) 

terminal,
3 

− Battery (+) 

terminal

4 

− 5

Less than 2 ohms

1

2 3

4

5

1

3

4

5

AC204637

RELAY SIDE

AB

THEFT-ALARM HORN RELAY

AC204183

CONNECTOR : A-11X

RELAY BOX SIDE

AE

2 1

5

4

3

A-11X

1

2

3

4

5

ACX01571AC

CONNECTOR A-11X
(RELAY BOX SIDE)

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-488

STEP 6. Check the wiring harness between theft-alarm 
horn relay connector A-11X (terminals 3 and 5) and fusible 
link (1).
Q: Is the wiring harness between theft-alarm horn relay 

connector A-11X (terminals 3 and 5) and fusible link (1) 
in good condition?
YES : Replace the ETACS-ECU. All the vehicle horn 

(including the theft-alarm horn) should sound when 
the theft-alarm system is triggered.

NO :  The wiring harness may be damaged or the 

connector(s) may have loose, corroded or damaged 
terminals, or terminals pushed back in the connector. 
Repair the wiring harness as necessary. All the 
vehicle horn (including the theft-alarm horn) should 
sound when the theft-alarm system is triggered.

STEP 7. Check theft-alarm horn connector A-04 for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.
Q: Is theft-alarm horn connector A-04 in good condition?

YES : Go to Step 8.
NO :  Repair or replace the damaged component(s). Refer 

to GROUP 00E, Harness Connector Inspection 

P.00E-2

. All the vehicle horn (including the theft-alarm 

horn) should sound when the theft-alarm system is 
triggered.

ACX02274

FUSIBLE LINK (1)

AE

BATTERY

AC204183

CONNECTOR : A-11X

RELAY BOX SIDE

AE

2 1

5

4

3

A-11X

AC204167

CONNECTOR : A-04

HARNESS 
SIDE

A-04(B)

A-04(B)

AB

1