M-ASTC-ECU


ABS-ECU, active stability control system ECU, and active traction control system ECU are integrated into one in order to achieve integrated control over driving power and braking force in association of ASTC-ECU with ABS.

ABS HYDRAULIC PRESSURE CONTROL


This is basically the same as for the previous PAJERO.

EBD HYDRAULIC PRESSURE CONTROL


This is basically the same as for the previous PAJERO.

INITIAL CHECK, STARTING-OFF CHECK


The ASTC-ECU has self diagnosis function and execute initial check when ignition switch is turned on and after vehicle starts to drive. (Approximately 8 km/h.) The ASTC-ECU actuates relays and valves to check them. Warning lamps will illuminate until the ECU judges system status is normal. Some failures needs to drive to check them. If these malfunctions are detected last ignition on, warning lamps will illuminate until start to drive. Some checks are doing all time when ignition switch is on.

STARTING-OFF CHECK


The ASTC-ECU carried out the following checks at the point where the vehicle speed reaches 8 km/h.

Solenoid valve check (during initial starting off* only)


The control solenoid valves and switch solenoid valves inside the HBB are energised for a short period of time to check the driving of each solenoid valve.
note *:The initial starting-off means the time when the vehicle first starts of after the ignition switch is turned to the ON position.

WHEEL SPEED SENSOR CHECK


The ASTC-ECU checks whether any of the wheel speed sensors do not input signals when the vehicle start off.

CONSTANT CHECKS


The ASTC-ECU carries out the following constant checks after the initial check when the ignition switch is at the ON position.

ASTC-ECU


Self-diagnosis of the ASTC-ECU itself is carried out.

ECU power supply


It checks whether the ECU power supply voltage is within the operating range.

VALVE RELAY




WHEEL SPEED SENSOR




G AND YAW RATE SENSOR




STOP LAMP SWITCH


It monitors the output voltages for the stop lamp switch signal lines and detects for short-circuits and ON problems in the stop lamp switch circuit.

CONTROL SOLENOID VALVES AND SWITCH SOLENOID VALVES


It checks that the output signals from the ASTC-ECU itself match the solenoid valve drive conditions.

STEERING WHEEL SENSOR


It checks that the steering wheel angle information sent from the steering wheel sensor via the CAN bus line is normal.

ACTIVE STABILITY AND TRACTION CONTROL SYSTEM (ASTC)



SYSTEM COMPOSITION


Active Stability and Traction Control System is composed of same components of ABS and added sensors and HBB function as follows. Yaw rate sensor, steering wheel sensor, master cylinder pressure sensor, HBB with active pressurization function.

ACTIVE STABILITY CONTROL SYSTEM


ASTC-ECU detects the vehicle movement based on the information received from each sensor and calculates ideal vehicle movement model. Based on the comparison of two results, yaw moment of the vehicle is generated by controlling braking force applied to certain wheels and understeer/oversteer is suppressed by controlling the engine output so that the vehicle movement can become similar to the calculated model.

EXAMPLE OF ACTIVE STABILITY CONTROL SYSTEM ON




The active stability control system changes the balance of braking force and cornering force to generate yaw moment so that the vehicle balance can be controlled.
For example, if the vehicle tends to be understeer on the slippery road surface against the driver’s intention, yaw moment towards suppression of understeer (rotating force) is generated by increaseing braking force applied to the rear inner wheels. On the contrary, if the vehicle tends to be oversteer, yaw moment towards suppression of oversteer (counter-rotating force) is generated by increasing braking force applied to the front outer wheels. If the vehicle is determined as speeding, deceleration of the vehicle for stable and safe cornering can be achieved by reducing the engine output.

EXAMPLE OF BRAKING EFFECT





COOPERATIVE CONTROL


Active stability control system transmits and receives data receives data required for controlling ABS and active traction control system so that cooperative control can be achieved.
Control system
Control features
ABS
The system cooperates with ABS control while the active stability control system is activated so that ABS performance can be improved.
Active traction control system
The system cooperates with the active traction control system to prevent excessive wheel spin, which causes unstable vehicle movement when the accelerator pedal is depressed.

ACTIVE TRACTION CONTROL SYSTEM CONTROL




Active traction control system automatically applies braking force to the freewheeling drive wheels caused by driving on the partially low-friction efficiency road surface and improper contact of wheels with the road so that loss of driving power caused by the freewheeling drive wheels can be prevented.
For example, when the vehicle is driving off road, application of braking force to the freewheeling front left and rear right wheels can give driving power to not freewheeling front right and rear left wheels so that evacuation capability equivalent to differential lock can be provided.

FAIL-SAFE DIAGNOSTIC FUNCTION


ASTC-ECU monitors input and output signals any time and if any abnormality is detected in the system, fail signals are output to illuminate respective indicator lamp and provide control according to trouble symptoms as shown in the following table. (When ABS is faulty, the active stability control system and the active traction control system functions are disabled, but the other functions are not disabled when the active stability control system and the active traction control system are faulty. It should be noted that a method of illumination depends on the micro computer for monitoring.)
In addition, ASTC-ECU is equipped with the following functions to facilitate system inspections:

All of the above-mentioned items can be tested by the M.U.T.-III.

FAIL-SAFE FUNCTION


Diagnosis code No.
Item
ABS control
EBD control
Active stability control
Active traction control
Control by engine output
Control by braking force
Control by engine output
Control by braking force
11
Wheel speed sensor (FR) open circuit or short circuit
Control disabled

  • Normal control when one or two wheels are defective.
  • Control disabled when three or four wheels are defective.

Control disabled
Control disabled
Control disabled
Control disabled
12
Wheel speed sensor (FL) open circuit or short circuit
13
Wheel speed sensor (RR) open circuit or short circuit
14
Wheel speed sensor (RL) open circuit or short circuit
16*
ASTC-ECU power supply system
Control disabled
Control disabled
Control disabled
Control disabled
Control disabled
Control disabled
21
Wheel speed sensor (FR) system
Control disabled

  • Normal control when one or two wheels are defective.
  • Control disabled when three or four wheels are defective.

Control disabled
Control disabled
Control disabled
Control disabled
22
Wheel speed sensor (FL) system
23
Wheel speed sensor (RR) system
24
Wheel speed sensor (RL) system
25
The difference diameter tyre
Control disabled
Normal control
Control disabled
Control disabled
Control disabled
Control disabled
31
Ignition switch (IG2) system
Not applicable
Not applicable
Not applicable
Not applicable
Not applicable
Not applicable
33
Stoplamp switch system
Control disabled
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
34
CAN communication system
Normal control
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
35
PCM (engine) system
Not applicable
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
36
Communication system with PCM (engine)
37
PCM (A/T) system
Not applicable
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
38
Communication system with PCM (A/T)
41
Control solenoid valve (FR) system
Control disabled
Control disabled
Control disabled
Control disabled
Control disabled
Control disabled
42
Control solenoid valve (FL) system
43
Control solenoid valve (RR) system
44
Control solenoid valve (RL) system
45
Switch solenoid valve (SA1) system
Fail-safe mode control
Fail-safe mode control
Control disabled
Control disabled
Control disabled
Control disabled
46
Switch solenoid valve (SA2) system
47
Switch solenoid valve (SA3) system
48
Switch solenoid valve (STR) system
51
Valve relay ON defective
Control disabled
Control disabled
Control disabled
Control disabled
Control disabled
Control disabled
52
Valve relay OFF defective
Control disabled
Control disabled
Control disabled
Control disabled
Control disabled
Control disabled
53
Motor system
Control disabled
Normal control
Control disabled
Control disabled
Control disabled
Control disabled
54
Motor relay system
Open circuit defective
Control disabled
Normal control
Control disabled
Control disabled
Control disabled
Control disabled
Defects except for open circuit
Normal control
Normal control
Normal control
Normal control
Normal control
Normal control
55
Motor system
Control disabled
Normal control
Control disabled
Control disabled
Control disabled
Control disabled
56
Pressure switch system
Control disabled
Normal control
Control disabled
Control disabled
Control disabled
Control disabled
57
Accumulator pressure low
Control disabled
Normal control
Control disabled
Control disabled
Control disabled
Control disabled
58
Power supply drive circuit system
Not applicable
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
61
Master cylinder pressure sensor system
Normal control
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
63
G sensor output error
Fail-safe mode control
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
64
G sensor clogging defect
Fail-safe mode control
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
65
G sensor self-diagnosis error
Fail-safe mode control
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
66
Steering wheel sensor self-diagnosis error
Not applicable
Not applicable
Control disabled
Control disabled
Not applicable*
Not applicable*
67
Steering wheel sensor communication line error
Not applicable
Not applicable
Control disabled
Control disabled
Not applicable*
Not applicable*
68
Steering wheel sensor output error
Not applicable
Not applicable
Control disabled
Control disabled
Not applicable*
Not applicable*
71
Yaw rate sensor self-diagnosis error
Not applicable
Not applicable
Control disabled
Control disabled
Not applicable
Not applicable
72
Yaw rate sensor 0-point error
Not applicable
Not applicable
Control disabled
Control disabled
Not applicable
Not applicable
73
Yaw rate sensor output error
Not applicable
Not applicable
Control disabled
Control disabled
Not applicable
Not applicable
74
G and yaw rate sensor communication error
Fail-safe mode control
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
75
Transfer switch defect
Not applicable
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
76
G sensor error
Not applicable
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
77
Yaw rate sensor error
Not applicable
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
78
Incorrect PCM
Not applicable
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
81
G sensor initialization incomplete
Control disabled
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
82
Yaw rate sensor initialization incomplete
Not applicable
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
83
Steering sensor initialization incomplete
Not applicable
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
84
Transfer switch initialization incomplete
Not applicable
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
85
Master cylinder pressure sensor initialization incomplete
Not applicable
Not applicable
Control disabled
Control disabled
Control disabled
Control disabled
note *: Vehicle for 3800, active traction control system is disabled at 2H mode.

INDICATOR LAMP FUNCTION


Diagnosis code No.
Item
Brake warning lamp
ABS warning lamp
Active stability control system ON indicator/Active traction control system ON indicator
Active stability control OFF indicator
11
Wheel speed sensor (FR) open circuit or short circuit

  • off when one or two wheels are defective.
  • Illuminates when three or four wheels are defective.

Illuminates
Illuminates
Illuminates
12
Wheel speed sensor (FL) open circuit or short circuit
13
Wheel speed sensor (RR) open circuit or short circuit
14
Wheel speed sensor (RL) open circuit or short circuit
16*
M-ASTC-ECU power supply system
Illuminates
Illuminates
Illuminates
Illuminates
21
Wheel speed sensor (FR) system

  • off when one or two wheels are defective.
  • Illuminates when three or four wheels are defective.

Illuminates
Illuminates
Illuminates
22
Wheel speed sensor (FL) system
23
Wheel speed sensor (RR) system
24
Wheel speed sensor (RL) system
25
The difference diameter tyre
off
Illuminates
Illuminates
Illuminates
31
Ignition switch (IG2) system
Illuminates
off
off
off
33
Stoplamp switch system
off
Illuminates
Illuminates
Illuminates
34
CAN communication system
off
Illuminates
Illuminates
Illuminates
35
PCM (engine) system
off
off
Illuminates
Illuminates
36
Communication system with PCM (engine)
37
PCM (A/T) system
off
off
Illuminates
Illuminates
38
Communication system with PCM (A/T)
41
Control solenoid valve (FR) system
Illuminates
Illuminates
Illuminates
Illuminates
42
Control solenoid valve (FL) system
43
Control solenoid valve (RR) system
44
Control solenoid valve (RL) system
45
Switch solenoid valve (SA1) system
Illuminates
Illuminates
Illuminates
Illuminates
46
Switch solenoid valve (SA2) system
47
Switch solenoid valve (SA3) system
48
Switch solenoid valve (STR) system
51
Valve relay ON defective
Illuminates
Illuminates
Illuminates
Illuminates
52
Valve relay OFF defective
Illuminates
Illuminates
Illuminates
Illuminates
53
Motor system
Illuminates
Illuminates
Illuminates
Illuminates
54
Motor relay system
Open circuit
Illuminates
Illuminates
Illuminates
Illuminates
Other than open circuit
Illuminates
off
off
off
55
Motor system
Illuminates
Illuminates
Illuminates
Illuminates
56
Pressure switch system
Illuminates
Illuminates
Illuminates
Illuminates
57
Accumulator pressure low
Illuminates
Illuminates
Illuminates
Illuminates
58
Power supply drive circuit system
Illuminates
off
off
off
61
Master cylinder pressure sensor system
off
Illuminates
Illuminates
Illuminates
63
G sensor output error
off
Illuminates
Illuminates
Illuminates
64
G sensor clogging defect
off
Illuminates
Illuminates
Illuminates
65
G sensor self-diagnosis error
off
Illuminates
Illuminates
Illuminates
66
Steering wheel sensor self-diagnosis error
off
off
Illuminates
Illuminates
67
Steering wheel sensor communication line error
off
off
Illuminates
Illuminates
68
Steering wheel sensor output error
off
off
Illuminates
Illuminates
71
Yaw rate sensor self-diagnosis error
off
off
Illuminates
Illuminates
72
Yaw rate sensor 0-point error
off
off
Illuminates
Illuminates
73
Yaw rate sensor output error
off
off
Illuminates
Illuminates
74
G and yaw rate sensor communication error
off
Illuminates
Illuminates
Illuminates
75
Transfer switch defect
off
off
Illuminates
Illuminates
76
G sensor error
off
Illuminates
Illuminates
Illuminates
77
Yaw rate sensor error
off
off
Illuminates
Illuminates
78
Incorrect PCM
off
off
Illuminates
Illuminates
81
G sensor initialization incomplete
Not applicable
Not applicable
Flashes
Illuminates
82
Yaw rate sensor initialization incomplete
Not applicable
Not applicable
Flashes
Illuminates
83
Steering sensor initialization incomplete
Not applicable
Not applicable
off
Illuminates
84
Transfer switch initialization incomplete
Not applicable
Not applicable
off
Illuminates
85
Master cylinder pressure sensor initialization incomplete
Not applicable
Not applicable
off
Illuminates

DIAGNOSIS CODE OUTPUT


The diagnostic function encompasses 53 items, and the diagnosis codes can be read using the M.U.T.-III. (Refer to Workshop Manual.)

DIAGNOSIS CODE MEMORY ERASING PROCEDURE


Diagnosis codes can be cleared from memory by using the M.U.T.-III. (Refer to Workshop Manual.)

DATA LIST OUTPUT


Among the ASTC-ECU input data, the following items can be read by using the M.U.T.-III.
Item No.
Check item
Inspection conditions
Normal condition
11
Front right wheel speed
Actually drive the vehicle
Speedometer display and M.U.T.-III display are identical
12
Front left wheel speed
13
Rear right wheel speed
14
Rear left wheel speed
16
APS
Actually drive the vehicle
The value of voltage rises to 0.5 V - 4.5 V
17
Engine Speed
Actually drive the vehicle
tachometer display and M.U.T.-III display are identical
19
G sensor output (Front and Rear)
Actually drive the vehicle
Indication varies between -14.7 and 14.7 m/s2
20
G sensor output (Left and Right)
21
Yaw-rate output
Actually drive the vehicle
Indication varies between -50 and 50 deg/s
22
G sensor output 1
Actually drive the vehicle
Indication varies between -14.7 and 14.7 m/s2
23
G sensor output 2
24
Master cylinder pressure sensor
Ignition switch: ON
Depress brake pedal gradually
The value of voltage rises to 0.5 V - 4.5 V
26
Transmission gear position
Actually drive the vehicle
Indication of shift lever position indicator is almost matched with that of M.U.T.-III
27
Shift lever position
Actually drive the vehicle
Shift lever position is almost matched with indication of M.U.T.-III
28
Engine type/Destination
Ignition switch: ON
Engine type and destination is almost matched with indication of M.U.T.-III
30
Transfer position
Actually drive the vehicle
Transfer shift lever position is almost matched with indication of M.U.T.-III
31
Battery voltage
Ignition switch: ON
Display battery voltage
32
Steering wheel operation
Ignition switch: ON
Turn the steering wheel from the neutral position
Approximately the same value as turning angle of steering wheel is diaplayed
36
Stop lamp switch
Ignition switch: ON
When depressing brake pedal
ON
When releasing brake pedal
OFF
37
Active stability control switch
Ignition switch: ON
Active stability control switch neutral position
OFF
Active stability control switch pushed
ON
75
Accelerator pedal position switch
Ignition switch: ON
Depress accelerator pedal
OFF
Release accelerator pedal
ON
76
Pressure switch (for low pressure warning)
With the pressure of pressure switch at 10.8 MPa or more
ON
77
Pressure switch (for pump control)
With the pressure of pressure switch at 16.1 MPa or more
ON
78
Valve relay
Valve relay activated
ON
Valve relay deactivated
OFF
79
Motor relay
Motor relay activated
ON
Motor relay deactivated
OFF
80
2H switch
Transfer lever position: 2H
ON
Transfer lever position: 4H, 4HLc, 4LLc
OFF
81
2/4H switch
Transfer lever position: 2H, 4H
ON
Transfer lever position: 4HLc, 4LLc
OFF
82
4H switch
Transfer lever position: 4H
ON
Transfer lever position: 2H, 4HLc, 4LLc
OFF
83
Center differential lock switch
Center differential lock switch position: ON
ON
Center differential lock switch position: OFF
OFF
84
4L switch
Transfer lever position: 4HLc, 4LLc
ON
Transfer lever position: 2H, 4H
OFF
85
Rear differential lock enguage
Rear differential lock enguage switch: ON
ON
Rear differential lock enguage switch: OFF
OFF
86
Rear differential lock switch
Rear differential lock switch: ON
ON
Rear differential lock switch: OFF
OFF
87
Rear differential lock indicator
Rear differential lock indicator: ON
ON
Rear differential lock indicator: OFF
OFF

ACTUATOR TEST


Solenoid valves can be activated forcibly by using the M.U.T.-III. In addition, the air bleeding mode for the active stability control system is set.
The actuator test is suspended when the ASTC system fails.
Item No.
Check item
Drive content
01
Soenoid valve (ABS) for front right wheel
Switch solenoid valve for HBB, and control solenoid valve corresponding to each channel
02
Soenoid valve (ABS) for front left wheel
03
Soenoid valve (ABS) for rear right wheel
04
Soenoid valve (ABS) for rear left wheel
05
Solenoid valve for front-right wheel
Switch solenoid valve of Active Stability Control System and control solenoid valve corresponding to each channel
06
Solenoid valve for front-left wheel
07
Solenoid valve for rear-right wheel
08
Solenoid valve for rear-left wheel
09
Bleeding (1)
Switch solenoid valve for HBB, and control solenoid valve OUT (FR, FL)
10
Bleeding (2)
Control solenoid valve for HBB OUT (RR, RL)
11
Pump motor
Drive pump motor for 1 second.
12
HBB buzzer
Drive HBB buzzer for 3 seconds.
13
Engine
Reduce engine torque.
14
Steering wheel sensor
Initialize steering wheel sensor.
15
Yaw rate sensor
Initialize yaw rate sensor.
16
G sensor
Initialize G sensor.
23
Brake warning lamp
Make the brake warning lamp flash twice.
24
ABS warning lamp
Make the ABS warning lamp flash twice.
25
Active Stability Control System ON indicator/Active Traction Control System ON indicator
Make Active Stability Control System ON indicator/Active Traction Control System ON indicator flash twice.
26
Active Stability Control System OFF indicator
Make Active Stability Control System OFF indicator flash twice.
note For the actuator operation pattern, refer to the Workshop Manual.