Mitsubishi Montero (2004+). Manual - part 1076

M-ASTC DIAGNOSIS

TSB Revision

MITSUBISHI ACTIVE SKID AND TRACTION CONTROL SYSTEM

35C-15

DTC 34: Defective CAN bus line

CAUTION

If the diagnostic trouble code(s), which indicate a defective CAN bus line, has been set, diagnose the 
CAN main bus line.

.

CIRCUIT OPERATION
 The M-ASTC-ECU gathers information through 
CAN_H (terminal 83) and CAN_L (terminal 84) bus 
lines from the power control module, the G and yaw 
rate sensor and the steering wheel sensor.

.

M-ASTC DTC SET CONDITION
DTC 34 is set if communication errors have hap-
pened in at least two of the relevant ECUs and/or 
sensors simultaneously, which are connected to 
each other through the CAN bus line.

.

TROUBLESHOOTING HINTS
The most likely causes for DTC 34 to set are:

• The CAN bus line is defective.

AC204606

Can Bus Communication Circuit

M-ASTC DIAGNOSIS

TSB Revision

MITSUBISHI ACTIVE SKID AND TRACTION CONTROL SYSTEM

35C-16

• The register is defective.

DIAGNOSIS 

Required Special Tools:

•  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

• MB991223: Harness Set

STEP 1. Diagnose CAN main bus line.

CAUTION

If DTC 34 is set, diagnose the CAN main bus line.
Diagnose the CAN main bus line. Refer to 

P.35C-61

.

Q: Have you completed checking or repairing the CAN 

main bus line?
YES : Go to Step 2.
NO :  Diagnose the CAN main bus line. Refer to 

P.35C-61

.

STEP 2. Recheck for diagnostic trouble code.
Q: Does DTC 34 reset?

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

M-ASTC DIAGNOSIS

TSB Revision

MITSUBISHI ACTIVE SKID AND TRACTION CONTROL SYSTEM

35C-17

DTC 35, 37, 78: Defective power control module

.

CIRCUIT OPERATION
The M-ASTC-ECU gathers information regarding the 
engine and automatic transmission, through the CAN 
bus line from the power control module.

.

M-ASTC DTC SET CONDITION
DTC 35 is set if the engine related data contains an 
error. DTC 37 is set if the automatic transmission 
related data contains an error. In this case, the PCM 
is sending data to the ECU, but the data contains a 
fault.

.

TROUBLESHOOTING HINTS
The most likely causes for DTC 35, 37, 78 to set are:

• The power control module is defective

• The M-ASTC-ECU is defective.

DIAGNOSIS 

Required Special Tools:

•  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

• MB991223: Harness Set

AC205062

CAN Bus Communication Circuit (powertrain control module)

AB

M-ASTC DIAGNOSIS

TSB Revision

MITSUBISHI ACTIVE SKID AND TRACTION CONTROL SYSTEM

35C-18

STEP 1. Using scan tool MB991958, read the MFI 
diagnostic trouble code.

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) Turn the ignition switch to the "ON" position.
(3) Check if the MFI DTC is set.
(4) Turn the ignition switch to the "LOCK (OFF)" position.
Q: Are MFI DTCs set?

YES : Diagnose the power control module. Refer to 

P.13A-26

.

NO :  Go to Step 2.

STEP 2. Check by the substitution of a known good 
M-ASTC-ECU (Recheck for diagnostic trouble code).
(1) Replace the M-ASTC-ECU with a know good unit.
(2) Check for DTC.
Q: Is DTC 35, 37 or 78 reset?

YES : Replace the power control module, and then go to 

Step 3.

NO :  Replace the M-ASTC-ECU, and then go to Step 3.

STEP 3. Recheck for diagnostic trouble code.
Q: Does DTC 35, 37 or 78 reset?

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

AC307591 AC

MB991911

MB991824

MB991827

AC307591

DATA LINK

CONNECTOR