Mitsubishi Montero Sport (2004+). Manual — part 703

AUTOMATIC TRANSMISSION DIAGNOSIS

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AUTOMATIC TRANSMISSION

23A-377

.

CIRCUIT OPERATION

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

sure switch is closed, PCM (terminal number 83)
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.

.

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

AC103771

CONNECTOR: C-09

AF

C-09

4

2

1

3

AC202442

22

2021

10

9

8

1718

6 7

19

1415

4 5

1112

1 2 3

13

16

CONNECTOR: C-41

C-41

AB

PCM

89
98

88
97

76 77

87

86

83
94

84
95

85

96

80
92

81
93

79

78
90 91

82

74

71 72 73

75

AC202312

CONNECTOR: C-91

AB

C-91 (GR)

AUTOMATIC TRANSMISSION DIAGNOSIS

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AUTOMATIC TRANSMISSION

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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, the scan tool

MB991958 display should be "ON."

• When the A/C is not in operation, the 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.00-7

.

NO : Go to Step 2.

STEP 2. Check dual pressure switch connector A-23 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

.

AK303629AB

MB991911

MB991827

MB991824

16-PIN

AC202889

1 2

AB

CONNECTOR: A-23

A-23 (BR)

AUTOMATIC TRANSMISSION DIAGNOSIS

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AUTOMATIC TRANSMISSION

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STEP 3. Measure the power supply voltage at dual
pressure switch connector A-23.

(1) Disconnect the connector A-23 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 1 and ground.

• 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.

STEP 4. Measure the power supply voltage at automatic
compressor controller connector C-09 by backprobing.

(1) Do not disconnect connector C-09.
(2) Start the engine and run at idle.

(3) Operate the A/C.

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

backprobing.

• 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 8.
NO : Go to Step 5.

AC202889

1 2

AB

CONNECTOR: A-23

A-23 (BR)

AC004990

1

2

A-23 HARNESS CONNECTOR:
COMPONENT SIDE

AC

AC103771

CONNECTOR: C-09

AF

C-09

4

2

1

3

1 2 3 4

AC004991

C-09 HARNESS CONNECTOR:
HARNESS SIDE

AC

AUTOMATIC TRANSMISSION DIAGNOSIS

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AUTOMATIC TRANSMISSION

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STEP 5. Check automatic compressor controller connector
C-09 and intermediate connector C-41 for loose, corroded
or damaged terminals, or terminals pushed back in the
connector.

Q: Are the connectors and terminals in good condition?

YES : Go to Step 6.
NO : Repair or replace the damaged components. Refer to

GROUP 00E, Harness Connector Inspection

P.00E-2

.

STEP 6. Check harness for short circuit to ground between
dual pressure switch connector A-23 terminal 1 and
automatic compressor controller connector C-09 terminal
2.

Q: Is the harness wire in good condition?

YES : Go to Step 7.
NO : Repair or replace the harness wire.

AC103771

CONNECTOR: C-09

AF

C-09

4

2

1

3

AC202442

22

2021

10

9

8

1718

6 7

19

1415

4 5

1112

1 2 3

13

16

CONNECTOR: C-41

C-41

AB

AC202889

1 2

AB

CONNECTOR: A-23

A-23 (BR)

AC103771

CONNECTOR: C-09

AF

C-09

4

2

1

3