Mitsubishi Montero (2002-2004). Manual - part 1109

M-ASTC DIAGNOSIS

TSB Revision

MITSUBISHI ACTIVE SKID AND TRACTION CONTROL SYSTEM

35C-53

.

CIRCUIT OPERATION
If the transfer gear is engaged, a relevant switch is 
turned on. When the switch is turned on, the current 
from the M-ASTC-ECU is grounded. 

.

M-ASTC DTC SET CONDITION
DTC 75 is set when the 2WD/4WD detection switch, 
the center differential detection switch, the 2WD 
detection switch, 4LLc detection switch or the 4H 
detection switch or their relevant circuits is defective.

.

TROUBLESHOOTING HINTS
The most likely causes for DTC 75 to set are:

• The 2WD/4WD detection switch is defective.

• The center differential detection switch is defec-

tive.

• The 2WD detection switch is defective.

• The 4LLc detection switch is defective.

• The 4H detection switch is defective.

• Damaged harness wires and connectors

• The M-ASTC-ECU is defective.

DIAGNOSIS 

Required Special Tools:

• MB991223: Harness Set

• MB991502: Scan Tool (MUT-II)

STEP 1. Using scan tool MB991502, check the transfer 
diagnostic trouble code (DTC).

CAUTION

To prevent damage to the scan tool always turn the igni-
tion switch to "LOCK" (OFF) position before connecting or 
disconnecting the scan tool.

1. Connect scan tool MB991502 to the data link connector. 

2. Turn the ignition switch to the "ON" position.
3. Check the transfer diagnostic trouble code.

Q: Does the transfer set any DTC?

YES : Diagnose the transfer-ECU. Refer to

P.23Ab-43

.

NO :  Go to Step 2.

AC204395

CONNECTORS: C-05, C-06, C-10, C-11, C-12

C-05(BR)

AD

C-06(B)

C-11(W)

C-12(BR)

C-10(B)

AC204176

CONNECTORS: E-121, E-123

E-121

AO

E-123(GR)

ACX01539

16-pin

MB991502

AI

M-ASTC DIAGNOSIS

TSB Revision

MITSUBISHI ACTIVE SKID AND TRACTION CONTROL SYSTEM

35C-54

STEP 2. Check M-ASTC-ECU connector E-121.
Q: Is M-ASTC-ECU connector E-121 in good condition?

YES : Go to Step 3.
NO :  Repair or replace the connector, and then go to Step 

4.

AC204176

CONNECTOR: E-121

HARNESS SIDE

AC

71

77

83

72

78

84

73

79

85

74

80

75

81

86

76

82

87

M-ASTC DIAGNOSIS

TSB Revision

MITSUBISHI ACTIVE SKID AND TRACTION CONTROL SYSTEM

35C-55

STEP 3. Check the wiring harness from the M-ASTC-ECU 
connector E-121 (terminals 75, 80, 86, 76 and 87) to 2WD/
4WD detection switch connector C-10 (terminal 1), the 
center differential detection switch connector C-12 
(terminal 1), the 2WD detection switch connector C-06 
(terminal 1), the 4LLc detection switch connector C-05 
(terminal 1) and 4H detection switch connector C-11 
(terminal 1).
NOTE: Also check intermediate connector E-123 for loose, cor-
roded, or damaged terminals, or terminals pushed back in the 
connector. If intermediate connector E-123 is damaged, repair 
or replace the damaged component(s) as described in GROUP 
00E, Harness Connector Inspection 

P.00E-2

. If the connector 

has been repaired or replaced, go to Step 4.
Q:  Is the wiring harness from the M-ASTC-ECU connector 

E-121 (terminals 75, 80, 86, 76 and 87) to 2WD/4WD 
detection switch connector C-10 (terminal 1), the center 
differential detection switch connector C-12 (terminal 1), 
the 2WD detection switch connector C-06 (terminal 1), 
the 4LLc detection switch connector C-05 (terminal 1) 
and 4H detection switch connector C-11 (terminal 1) in 
good condition?
YES : Replace the M-ASTC-ECU, and then go to Step 4.
NO :  Repair the wiring harness, and then go to Step 4.

AC204510 AB

C-05(BR)

C-10(B)

C-12(BR)

C-06(B)

C-11(W)

CONNECTORS: C-05, C-06, C-10, C-11, C-12

C-06(B)

HARNESS SIDE

C-05(BR)

HARNESS SIDE

C-11(W)

HARNESS SIDE

C-12(BR)

HARNESS SIDE

C-10(B)

HARNESS SIDE

1

1

1

1

1

AC204194

CONNECTORS: E-121, E-123

E-123(GR)

E-123

HARNESS SIDE

AG

E-121

E-121

HARNESS SIDE

71

77

83

72

78

84

73

79

85

74

80

75

81

86

76

82

87

2

6

14

7

9 8

10

4

12

3

11

19

16

1817

15

1

5

13

M-ASTC DIAGNOSIS

TSB Revision

MITSUBISHI ACTIVE SKID AND TRACTION CONTROL SYSTEM

35C-56

STEP 4. Check the diagnostic trouble code.
Q: Does DTC 75 reset?

YES : Return to Step 1.
NO :  The procedure is complete.

DTC 81: G sensor not initialized
DTC 82: Yaw rate sensor not initialized

.

M-ASTC DTC SET CONDITION
DTCs 81 and 82 will be set when a new G and yaw 
rate sensor is not initialized (i.e. reference point posi-
tioning) executing No.16 "G SNSR: " and No.15 
"YAWRATE SNS: 0" on the Actuator test.

.

TROUBLESHOOTING HINTS
The most likely causes for DTC 81, 82 to set are:

• The G and yaw rate sensor is defective

• The M-ASTC-ECU is defective.

DIAGNOSIS 

Required Special Tools:

• MB991502: Scan Tool (MUT-II)

STEP 1. Execute the Actuator test.

1. Confirm that the vehicle is not canted to one side or corner.
2. Place the selector lever in the "P" position.
3. Execute the Actuator test as follows.

• No.15 YAWRATE SNS: 0

• No.16 G SNSR: 0

Q: Does the M-ASTC-ECU set DTC 81 or 82?

YES : Replace the G and yaw rate sensor. Refer to 

P.35C-

207

. Then go to STEP 2.

NO :  Go to Step 2.

STEP 2. Check the diagnostic trouble code.
Q: Does DTC 81, 82 reset?

YES : Replace the M-ASTC-ECU.
NO :  The procedure is complete.