MoTeC MDC2 User Manual
MDC2
Mitsubishi Diff Controller
User Manual
© Copyright – MoTeC Pty Ltd – 2001-2009
The information in this document is subject to change without notice.
While every effort is taken to ensure correctness, no responsibility will be taken for the consequences of any inaccuracies or omissions in this manual.
23 June, 2009
Contents
Introduction ......................................................................... 1
MDC2 Functionality ............................................................ 2
Mode selection ................................................................................................... 2
Lock Calculation ................................................................................................. 2
Slip Control ......................................................................................................... 3
Slip control example ................................................................................ 3
Speed Measurement .......................................................................................... 3
Speed Calculations ................................................................................. 4
Handbrake Override ........................................................................................... 4
Throttle Calibration ............................................................................................. 4
Steering Position Measurement .......................................................................... 4
Hydraulic Pressure Pump Control ...................................................................... 5
Hydraulic Pressure Pump Priming Mode ............................................................ 5
Communications ................................................................................................. 5
Main Vehicle CAN Bus ............................................................................ 5
Yaw/G Sensor CAN bus .......................................................................... 6
Data Logging ........................................................................................... 6
PC Connection ........................................................................................ 6
Miscellaneous functions ..................................................................................... 7
Fault indication ........................................................................................ 7
MDC2 Manager .................................................................... 8
Computer requirements ...................................................................................... 8
Connecting to a MDC2 ....................................................................................... 8
Installing MDC2 Manager ................................................................................... 8
Managing Configurations .................................................................................... 8
Changing Configurations .................................................................................... 8
User Mode Tables ................................................................................... 8
File | Setup | Input Setup ......................................................................... 9
File | Setup | Input Tables ...................................................................... 10
File | Setup | Output Setup .................................................................... 10
File | Setup | User Modes ...................................................................... 11
Monitoring MDC2 Data ..................................................................................... 11
Sending Firmware ............................................................................................ 11
MDC2 Installation .............................................................. 12
Appendices ....................................................................... 13
Appendix A – Fault Codes ................................................................................ 13
Appendix B – MDC2 Pinout and Links .............................................................. 14
MDC2 Connector Pinout ....................................................................... 14
Appendix C – CAN Wiring Practices ................................................................. 15
Appendix D – ECU Communications ................................................................ 16
Appendix E – CAN Messages .......................................................................... 17
50Hz Messages .................................................................................... 17
25Hz Messages .................................................................................... 18
MoTeC MDC2 1 Introduction
Introduction
The MoTeC Mitsubishi Diff Controller 2 (MDC2) is a direct replacement for the Active Centre Diff (ACD) controller
in the Mitsubishi EVO X.
The MDC2 also supports centre diff control on Active Yaw Control (AYC) equipped vehicles however the yaw
control hardware is not used.
This manual covers the installation, configuration and functionality of the MDC2.
MoTeC MDC2 2 Functionality
MDC2 Functionality
Mode selection
There are six user selectable control modes, four of which are user configurable. The control modes can be
selected using the ACD toggle switch on the steering wheel.
The current mode is indicated in the top line of the dash centre display. Optionally, three mode lights (SNOW,
TARMAC and GRAVEL) can be wired directly to the MDC2 if the dash display is removed.
Control Mode Dash Display Top Line Lights (optional)
0% Lock Blank None
1 (Snow)
SNOW
2 (Gravel)
GRAVEL
3 (Tar)
TARMAC
4 (Gravel/Tar)
GRAVEL + TARMAC
/ (alternating)
Constant Lock
SNOW + GRAVEL + TARMAC
(flashing)
Note: If the mode has not changed for one minute then the current mode is saved and will be used next time the
MDC2 is powered on.
Lock Calculation
Lock percentage applied to the centre diff is determined primarily by the vehicle speed, throttle position or engine
efficiency point (from a MoTeC ECU), and front to rear wheel slip.
Each of the four user modes are configured with an acceleration table, a braking table, a desired slip table and
slip control parameters. Slip control may be disabled if not required.
The lock percentage for a user mode is determined according to the following strategy:
Vehicle
Speed
Throttle
Position or
Manifold
Pressure
Front & Rear
Speed
Accel
table
(% lock)
Brake
table
(% lock)
Desired
Slip table
(kph)
Slip
control
params
Brake
OFF
ON
Slip
Calculation
(% lock)
+ MIN
100%
Lock
0%
Lock
Handbrake
OFF
ON
% lock
MoTeC MDC2 3 Functionality
The lock percentage for the constant lock mode is determined according to the following strategy:
Const ant
lock %
0%
Lock
The constant lock % is equivalent to the maximum lock achieved by the Mitsubishi factory AYC / ACD controller.
The lock percentage is always 0% in the 0% lock mode.
Note: The handbrake status is ignored during a handbrake start from 0km/h – See Handbrake Override below.
For information on configuring the user modes see the MDC2 Manager section.
Handbrake
OFF
ON
% lock
Slip Control
The slip control strategy detects slip (i.e.: rear speed ≠ front speed) and increases diff lock to maintain slip close
to the value specified in the Desired Slip table. The Desired Slip table specifies the value above which additional
diff lock will be applied, according to the slip control setup parameters.
The calculation of lock percentage for slip control is determined by the Slip Control Range and Max Slip Control
Lock parameters which apply to all user modes.
The following algorithm determines the %lock for slip control. The desired slip is the output from the Desired Slip
table.
IF Rear Speed > Front Speed
THEN Measured Slip = Rear Speed – Front Speed
ELSE Measured Slip = Front Speed – Rear Speed
Slip Control Factor = (Measured Slip – Desired Slip) / Slip Control Range
Constrain Slip Control Factor to the range 0 to 1
Slip Diff Lock = Slip Control Factor * Max Slip Control Lock
NOTE: Slip is specified as speed difference between front and rear wheels, not as a ratio of the speeds.
The addition of the calculated slip diff lock percentage is shown in the lock percentage strategy above.
Slip control example
Max slip control = 10% lock
Slip control range = 20 km/h
Desired slip (from Desired Slip table) = 10km/h
For a measured slip of 15km/h, slip diff lock = ((15 – 10) / 20) * 10 = 2.5%
For a measured slip of 30km/h or above, slip diff lock = 10%
For information on configuring the slip control parameters, see Setup | User Modes in the MDC2 Manager
section.
Speed Measurement
The four wheel speeds are received on the CAN bus from the ABS module, or the four wheel speed sensors can
optionally be wired directly to the MDC2. If the ABS module is removed, the sensors must be directly connected
to the MDC2.
MoTeC MDC2 4 Functionality
When wired directly to the MDC2, the wheel speed inputs can be configured as hall effect or magnetic sensors
with adjustable thresholds, and individual sensors can be enabled or disabled. Magnetic sensor input thresholds
are individually configurable for front and rear sensor pairs according to the current front and rear speeds.
The speed calibration can be adjusted for different wheel sizes and sensor teeth.
Front, rear and vehicle speeds are calculated from the wheel speeds, and all speeds are transmitted in CAN
messages. These speeds can be logged by the MoTeC ADL (Advanced Dash Logger), or used in logging or
engine control strategies by the MoTeC M800 ECU.
For information on configuring speed inputs, see Setup | Input Setup in the MDC2 Manager section.
Speed Calculations
The method of calculating front, rear and vehicle speeds is dependent on the status of the brake input.
When the foot brake is applied, speeds are calculated as follows:
• Front Speed is the faster of the two front wheel speeds.
• Rear speed is the faster of the two rear wheel speeds.
• Vehicle speed is the faster of the calculated front speed and rear speed.
When the foot brake is not applied, speeds are calculated as follows:
• The front speed is the average of the two front wheel speeds, weighted 80% towards the slowest front
wheel speed. If one front wheel speed is less than half of the other front wheel speed, then front speed is
simply the faster of the two front wheel speeds.
• The rear speed is the average of the two rear wheel speeds, weighted 80% towards the slowest rear
wheel speed. If one rear wheel speed is less than half of the other rear wheel speed, then rear speed is
simply the faster of the two rear wheel speeds.
• The vehicle speed is the average of the front and rear speeds, weighted 80% towards the slowest speed.
If either the front or rear speed is less than half of the other speed, then vehicle speed is simply the faster
out of the front speed and rear speed.
If any wheel speed exceeds 300km/h, the sensor reading is ignored until its speed returns to below 300km/h for 2
seconds. This is to prevent erratic behaviour from noisy wiring or faulty sensors.
Handbrake Override
If the front wheel speed is 0km/h and the handbrake is active, the handbrake will then be ignored in all lock
calculations until the handbrake is released. This functionality allows the diff to be locked in preparation for takeoff
during a handbrake start.
Throttle Calibration
The throttle position is received on the CAN bus from the ECU, or a throttle position sensor can be optionally
wired directly to the MDC2.
The optional throttle position sensor input can be calibrated using a table to convert voltage to throttle position.
This allows non-linear calibration of throttle position to more closely model the change in torque vs. throttle
butterfly angle.
The MDC2 Manager configuration program allows throttle input voltages to be read directly from the MDC2 in
order to perform 0% and 100% calibrations.
For information on calibrating the throttle input, see Setup | Input Setup in the MDC2 Manager section.
Steering Position Measurement
The steering position is received on the CAN bus from the steering position sensor.
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