Mitsubishi Montero (2004+). Manual - part 941

AUTOMATIC TRANSMISSION DIAGNOSIS

TSB Revision

AUTOMATIC TRANSMISSION

23A-339

INSPECTION PROCEDURE 15: Vehicle Shifts Differently with A/C Engaged

AC205255 AB

Dual Pressure Switch System Circuit

AUTOMATIC TRANSMISSION DIAGNOSIS

TSB Revision

AUTOMATIC TRANSMISSION

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.

CIRCUIT OPERATION

• When the A/C is turned ON and the dual pres-

sure switch is closed, PCM (terminal 69) receives 
battery voltage and then determines the A/C 
compressor has been signaled to engage.

• When the A/C compressor is engaged, the PCM 

increases line pressure and briefly delays shift 
points to compensate for the additional engine 
load.

.

COMMENT
The cause is probably a faulty dual pressure switch 
circuit or a defective PCM.

.

AC204185

CONNECTORS : A-03, A-22

A-03 (B)

A-22

A-03

AP

A-22 (BR)

6

12

5

3 4

2

1

9 10

8

7

11

1 2

AC204188

CONNECTORS : D-23, D-28, D-119

D-23 (B)

D-23, D-119

D-119 (B)

BE

D-28

D-28

20

10

19

9

17

7

16

6

14

4

3

13

5

15

11

1 2

12

8

18

2 3

27

32

28

33

16

15

4 5

19

18

29

17

34

7 8

35

22

21

9 10

30

36

31

37

25

24

23

6

20

1

14

26

11

13

12

38

AC204681AC

CONNECTOR: D-134

D-134 (GR)

61 62

63 64

65 66 67 68 69 70 71 72 73

82

89

81

88

80

79

78

77

87

86

85

76

75

74

84

83

AUTOMATIC TRANSMISSION DIAGNOSIS

TSB Revision

AUTOMATIC TRANSMISSION

23A-341

TROUBLESHOOTING HINTS (THE MOST LIKELY 
CAUSES FOR THIS CASE:)

• Malfunction of the dual pressure switch

• Damaged harness, connector

• Malfunction of A/C system

• Malfunction of the PCM

DIAGNOSIS

Required Special Tool:

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

• MB991824: V.C.I.

• MB991827: MUT-III USB Cable

• MB991911: MUT-III Main Harness B

STEP 1. Using scan tool MB991958, check data list item 65: 
Dual Pressure 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) Start the engine and run at idle.
(3) Set scan tool MB991958 to data reading mode.

• Item 65: Dual Pressure Switch.

• When the A/C is in operation, scan tool MB991958 

display should be "ON."

• When the A/C is not in operation, scan tool 

MB991958 display should be "OFF."

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the switch operating properly?

YES : It can be assumed that this malfunction is intermittent. 

Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

− How to 

Cope with Intermittent Malfunction 

P.00-6

.

NO :  Go to Step 2.

STEP 2. Check dual pressure switch connector A-22 for 
loose, corroded or damaged terminals, or terminals 
pushed back in the connector.
Q: Are the connector and terminals in good condition?

YES : Go to Step 3.
NO :  Repair or replace the damaged components. Refer to 

GROUP 00E, Harness Connector Inspection 

P.00E-2

.

AC307591 AC

MB991911

MB991824

MB991827

AC307591

DATA LINK

CONNECTOR

AC204167

CONNECTOR : A-22

AV

A-22 (BR)

A-22

1 2

AUTOMATIC TRANSMISSION DIAGNOSIS

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STEP 3. Measure the power supply voltage at dual 
pressure switch connector A-22.
(1) Disconnect the connector A-22 and measure at the harness 

side.

(2) Start the engine and run at idle.
(3) Operate the A/C.

(4) Measure the voltage between terminal 2 and ground.

• The voltage should measure battery positive voltage.

(5) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage battery positive voltage?

YES : Go to Step 10.
NO :  Go to Step 4.

AC204167

CONNECTOR : A-22

AV

A-22 (BR)

A-22

1 2

AC204918 AB

2 1

A-22 HARNESS CONNECTOR : 
COMPONENT SIDE