Mitsubishi Montero (2004+). Manual - part 1116

M-ASTC DIAGNOSIS

TSB Revision

MITSUBISHI ACTIVE SKID AND TRACTION CONTROL SYSTEM

35C-175

NOTE: Also check the joint between the communication line 
(connected to the power control module) and the CAN main 
bus line.

CAUTION

If there is a problem in the CAN bus line or the connectors 
on the control wiring harness assembly (the wiring har-
ness connected to the M-ASTC-ECU, the power control 
module and intermediate connector E-123), do not attempt 
to repair the wiring harness or connector(s), but replace 
the wiring harness assembly. If a wire is added or the con-
nector(s) are repaired, an error in the CAN communication 
may be caused.
Q: Is the wiring harness between power control module 

connector D-134 and the CAN main bus line in good 
condition?
YES : Go to Step 4.
NO :  Replace the control wiring harness assembly.

STEP 4. Replace the M-ASTC-ECU.

After the M-ASTC-ECU is replaced, retest the system.
Q: Has the trouble symptom been eliminated?

YES (the trouble symptom has been eliminated) : The 

procedure is complete.

NO (the trouble symptom has not been eliminated) : 

Replace the power control module.

M-ASTC DIAGNOSIS

TSB Revision

MITSUBISHI ACTIVE SKID AND TRACTION CONTROL SYSTEM

35C-176

Diagnostic Item 6: CAN bus line diagnostics (between the main bus line and the steering wheel 
sensor)

CAUTION

Prior to this diagnosis procedure, diagnose the 
CAN main bus line.

CAUTION

Before checking CAN bus lines and their inter-
connected components, "ground" yourself, by 
touching a metal object such as an unpainted 
pipe, this will discharge any potentially damag-
ing 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 con-
nected through the CAN bus lines may be dam-
aged.

CAUTION

Disconnect the negative battery terminal when 
measuring the resistance value in the CAN bus 
line. If you fail to do so, the equipments con-
nected through the CAN bus lines may be dam-
aged.

CAUTION

Always use the test harness when measuring the 
voltage or resistance value at the female connec-
tor. If you fail to do so, connectors may be dam-
aged.

CAUTION

If there is a problem in the connector(s) (includ-
ing terminals) or wire(s) of the instrument panel 
wiring harness assembly (the wiring harness 
connected to the steering wheel sensor, the data 
link connector and the resistor) and the trans-
mission wiring harness assembly (the wiring har-
ness connected to the G and yaw rate sensor 
connector and intermediate connector E-123), 
cut and repair the defective wire so that the 
frayed end of the twisted wire should be within 
10 cm (4.0 inches). If it exceeds 10 cm (4.0 

inches), twist the wiring harness just like the 
original twisted wire. If the frayed end exceeds 10 
cm (4.0 inches), a communication error may be 
caused.

CAUTION

If you repair the CAN bus line of the instrument 
panel wiring harness assembly (the wiring har-
ness connected to the steering wheel sensor, the 
data link connector and the resistor) and the 
transmission wiring harness assembly (the wir-
ing harness connected to the G and yaw rate 
sensor connector and intermediate connector 
E-123), observe the precautions regarding how to 
repair wiring harness. If a new wire is added or a 
splice point is modified for the CAN_L or CAN_H 
line, an error in the CAN communication may be 
caused.

AC203824

CONNECTOR

TWISTED WIRE

AB

10 cm
 (4.0 inches)

M-ASTC DIAGNOSIS

TSB Revision

MITSUBISHI ACTIVE SKID AND TRACTION CONTROL SYSTEM

35C-177

This procedure diagnoses the shaded portion below.

AC203825AF

PROBABLE
TROUBLE
SPOT

G AND 
YAW RATE
SENSOR

POWER TRAIN
CONTROL 
MODULE

M-ASTC-ECU

STEERING 
WHEEL 
SENSOR

DATA LINK
CONNECTOR

RESISTOR

CAN Bus Communication Circuit (steering wheel sensor)

M-ASTC DIAGNOSIS

TSB Revision

MITSUBISHI ACTIVE SKID AND TRACTION CONTROL SYSTEM

35C-178

.

CIRCUIT OPERATION
The M-ASTC-ECU receives signals through the CAN 
bus line from the steering wheel sensor.

.

TECHNICAL DESCRIPTION (COMMENT)
If the M-ASTC-ECU has set DTC code 67, the wiring 
harness between the CAN main bus line and the 
steering wheel sensor, the steering wheel sensor 
itself or the M-ASTC-ECU may be defective.

.

TROUBLESHOOTING HINTS

• The CAN bus line between the CAN main bus 

line and the steering wheel sensor is defective.

• Damaged connector(s)

• The steering wheel sensor is defective.

• The M-ASTC-ECU is defective.

DIAGNOSIS 

Required Special Tools:

• MB991223: Harness Set

AC204170

CONNECTOR: D-131

BV

AC204172

CONNECTOR: D-225

AH