Mitsubishi Montero Sport (2004+). Manual - part 706

AUTOMATIC TRANSMISSION DIAGNOSIS

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AUTOMATIC TRANSMISSION

23A-389

CIRCUIT OPERATION
When the battery positive voltage from PCM (termi-
nal number 75) is grounded at auto-cruise con-
trol-ECU (terminal number 3), the auto-cruise
control-ECU emits an overdrive cancel signal. When
a malfunction of the auto-cruise control circuit
occurs, the transmission may downshift harshly with
the auto-cruise control engaged.

COMMENT
A malfunction may be present on the auto-cruise sig-
nal line circuit, auto-cruise control-ECU or the PCM.

TROUBLESHOOTING HINTS (The most likely
causes for this case:)

• Damaged harness, connector

• Malfunction of the PCM

• Malfunction of the auto-cruise control-ECU

AC202435

PCM

59
68

58
67

46 47

53
64

48
60 61

41 42 43

AC202435

PCM

CONNECTOR: C-91

C-91 (GR)

71 72 73 74

75 76

78 79 80 81 82 83 84 85 86 87 88

90 91

92 93 94

95 96

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 66:
Overdrive Off Signal (Auto-cruise control-ECU Signal).

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 prepare to test drive the vehicle.

(Operate the auto-cruise)

(3) Set scan tool MB991958 to data reading mode.

• Item 66: Overdrive Off Signal (Auto-cruise control-ECU

Signal).

• When driving at level road, the display should be

"OFF."

• When driving at uphill road, the display should be

"ON."

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the auto-cruise control-ECU 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 the auto-cruise system.

Check the auto-cruise system. Refer to GROUP 17,
Auto-cruise Control System Diagnostic Troubleshooting Strat-
egy

P.17-7

Q: Is the auto-cruise system operating properly?

YES : Go to Step 3.
NO : Repair it, then check the symptom.

AK303629AB

MB991911

MB991827

MB991824

16-PIN

AUTOMATIC TRANSMISSION DIAGNOSIS

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AUTOMATIC TRANSMISSION

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STEP 3. Measure the signal voltage at PCM connector C-91
by backprobing.

(1) Do not disconnect connector C-91.
(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal 75 and ground by

backprobing.

• The voltage should measure battery positive voltage.

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

YES : Go to Step 6.
NO : Go to Step 4.

AC202435

PCM

59
68

58
67

46 47

53
64

48
60 61

41 42 43

AC202435

PCM

CONNECTOR: C-91

C-91 (GR)

71 72 73 74

75 76

78 79 80 81 82 83 84 85 86 87 88

90 91

92 93 94

95 96

AC002097

C-91 HARNESS CONNECTOR:
HARNESS SIDE

AUTOMATIC TRANSMISSION DIAGNOSIS

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AUTOMATIC TRANSMISSION

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STEP 4. Check intermediate connector C-41 and PCM
connector C-91 for looser, corroded or damaged terminals,
or terminals pushed back in the connector.

Q: Are the connectors and terminals in good condition?

YES : Go to Step 5.
NO : Repair or replace the damaged components. Refer to

GROUP 00E, Harness Connector Inspection

P.00E-2

AC202442

2021

1718

6 7

1415

4 5

1112

1 2 3

CONNECTOR: C-41

C-41

AC202435

PCM

59
68

58
67

46 47

53
64

48
60 61

41 42 43

AC202435

PCM

CONNECTOR: C-91

C-91 (GR)

71 72 73 74

75 76

78 79 80 81 82 83 84 85 86 87 88

90 91

92 93 94

95 96

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