Mitsubishi Montero Sport (2004+). Manual - part 546

DOME LIGHT

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CHASSIS ELECTRICAL

54-171

INSPECTION PROCEDURE 2: Dome Light and Cargo Space Light Dimming Function does not Work 
Normally.

.

TECHNICAL DESCRIPTION (COMMENT)
The ETACS-ECU dims the dome light and cargo 
space light according to the input signals from the 
following switches:

• Ignition switch (IG1)

• Key reminder switch

• Door switches

• Driver's door lock actuator switch

If the dome light and cargo space light does not be 
dimmed normally, the relevant input signal circuit or 
the ETACS-ECU may be defective.

.

TROUBLESHOOTING HINTS

• Malfunction of the key reminder switch

• Malfunction of the door switches

• Malfunction of the driver's door lock actuator switch

• Malfunction of the ETACS-ECU 

• Damaged harness wires or connectors

DIAGNOSIS

Required Special Tools:

• MB991223: Test 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 (Vehicles without 

CAN communication system)

• MB991529: Diagnostic Trouble Code Check Harness

STEP 1. Check the ETACS-ECU power supply circuit.

Do all of the following functions work when the ignition switch is 
turned to the "LOCK" (OFF) position?

• Ignition key reminder tone alarm function

• Light reminder tone alarm function

• Central door locking system

• Ignition key hole illumination light

• Theft-alarm system

Q: Do any of the functions work?

YES : Go to Step 2 <when using scan tool MB991958> or 3   

<when using a voltmeter>.

NO :  Check the ETACS-ECU battery circuit. Refer to 

Inspection Procedure P-1 (

P.54-302

).

DOME LIGHT

TSB Revision

CHASSIS ELECTRICAL

54-172

STEP 2. Check the input signal (by using pulse check).

Check the input signals from the following switches:

• Ignition switch (IG1)

• Key reminder switch 

• All door switch

• Liftgate 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 MB991958 to the data link connector.
(2) Check that the tone alarm of scan tool MB991958 sounds 

when the input signal enters.

Q: Does the tone alarm of scan tool MB991958 sound when 

the input signal enters?
YES : Replace the ETACS-ECU. The dome light and cargo 

space light dimming function should work normally.

NO :  Check the relevant input signal circuit. Refer to 

P.54-162

.

STEP 3. Check the input signal (by using a voltmeter).

Check the input signals from the following switches:

• Ignition switch (IG1)

• Key reminder switch 

• All door switch

• Liftgate switch

(1) Use special tool MB991529 to connect a voltmeter between 

ground terminal 4 or 5 and ETACS-ECU terminal 9 of the 
data link connector.

(2) Check that the voltmeter indicator deflects once when the 

input signal enters.

Q: Does the voltmeter indicator deflect?

YES : Replace the ETACS-ECU. The dome light and cargo 

space light dimming function should work normally.

NO :  Check the relevant input signal circuit. 

AK303629AB

MB991911

MB991827

MB991824 

16-PIN

AC003527

GROUNDED TERMINAL

ETACS-ECU 
TERMINAL

MB991529

AB

HIGH-MOUNTED STOPLIGHT

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CHASSIS ELECTRICAL

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HIGH-MOUNTED STOPLIGHT

REMOVAL AND INSTALLATION

M1542005100292

AC002795 AB

1

2

3

4

REMOVAL STEPS

1.

COVER

2.

HIGH-MOUNTED STOPLIGHT 
UNIT

3.

BULB SOCKET 

4.

BULB

REMOVAL STEPS (Continued)

RHEOSTAT

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CHASSIS ELECTRICAL

54-174

RHEOSTAT

INSPECTION

M1542006100198

RHEOSTAT CHECK

1. Connect the battery and the test bulb (40W) as shown in the 

illustration. 

2. Operate the rheostat, and if brightness changes smoothly 

without switching off, rheostat function is normal.

AC002797 AB

40W