Mitsubishi Montero (2004+). Manual - part 1087

M-ASTC DIAGNOSIS

TSB Revision

MITSUBISHI ACTIVE SKID AND TRACTION CONTROL SYSTEM

35C-59

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

Initialize the M-ASTC-ECU (Recheck for diagnostic trouble 
code).

Initialize the M-ASTC-ECU (Refer to 

P.35C-213

), and check 

that the DTC sets.
Q: Does DTC 84 reset?

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

DTC 85: Master cylinder pressure sensor not initialized

.

CIRCUIT OPERATION
The pressure sensor, which is energized by the 
M-ASTC-ECU, monitors the brake fluid pressure 
applied by the master cylinder. If this pressure 
becomes low, the signal from this pressure sensor 
turns on the pressure switch.

.

M-ASTC DTC SET CONDITION
DTC 85 will be set when a new M-ASTC-ECU is not 
initialized.

.

TROUBLESHOOTING HINTS
The most likely causes for DTC 84 to set are:

• M-ASTC-ECU not initialized

• 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

Initialize the M-ASTC-ECU (Recheck for diagnostic trouble 
code).

Initialize the M-ASTC-ECU (Refer to 

P.35C-213

), and check 

that the DTC sets.
Q: Does DTC 85 reset?

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

M-ASTC DIAGNOSIS

TSB Revision

MITSUBISHI ACTIVE SKID AND TRACTION CONTROL SYSTEM

35C-60

CAN BUS LINE DIAGNOSTICS

Precautions on how to repair the CAN communication lines

M1353006000027

.

Precautions on how to repair the CAN bus lines

• If the CAN_L or CAN_H line on the main bus line 

or branch line is repaired, renew all the twisted 
wires between the end connectors. If the wiring 
harness is partially repaired, or only CAN_L or 
CAN_H line is repaired, noise suppression is 
deteriorated, causing a communication error.

• If the connector or wire on the main bus line or 

the branch wire is replaced, the frayed end of the 
twisted wire should be within 10 cm (4.0 inches) 
from the connector. If it exceeds 10 cm (4.0 
inches), twist the wiring harness just like the orig-
inal twisted wire. If the frayed end exceeds 10 cm 
(4.0 inches), noise suppression is deteriorated, 
causing a communication error.

• If a branch wire is repaired, splice a new wire 

directly into the main bus line. If a new wire is 
spliced into the branch line, which is connected to 
another device, a CAN communication error will 
be caused.

.

Precautions on how to repair the terminator 
resistor
If one-side terminator resistor is broken, the CAN 
communication will continue although noise suppres-
sion is deteriorated. In this case, no DTC may be set. 
Check the system regardless of whether a DTC is 
set or not. If any damage is found, replace the termi-
nator resistor.

AC204696

ADDED WIRE

NO GOOD

AB

AC203824

CONNECTOR

TWISTED WIRE

AB

10 cm
 (4.0 inches)

AC202856

ECU

ECU

ECU

ECU

GOOD

NO GOOD

TERMINATOR RESISTOR

OPEN
CIRCUIT
POINT

OPEN
CIRCUIT
POINT

TERMINATOR RESISTOR

AB

M-ASTC DIAGNOSIS

TSB Revision

MITSUBISHI ACTIVE SKID AND TRACTION CONTROL SYSTEM

35C-61

Diagnostic Item 1: CAN main bus line diagnostics

CAUTION

Before checking CAN bus lines and their interconnected components, "ground" yourself, by touching 
a metal object such as an unpainted pipe, this will discharge any potentially damaging static that may 
have built up.

CAUTION

When measuring resistance value or voltage in CAN bus lines, use a digital multimeter. If not using a 
digital multimeter, the equipments connected through the CAN bus lines may be damaged.

CAUTION

Disconnect the negative battery terminal when measuring the resistance value in the CAN bus line. If 
you fail to do so, the equipments connected through the CAN bus lines may be damaged.

CAUTION

Always use the test harness when measuring the voltage or resistance at the female connector. If you 
fail to do so, connectors may be damaged.

M-ASTC DIAGNOSIS

TSB Revision

MITSUBISHI ACTIVE SKID AND TRACTION CONTROL SYSTEM

35C-62

AC204606

Can Bus Communication Circuit

AC204170

CONNECTOR: D-117

BS