MoTeC MDC User Manual
MDC
Mitsubishi Diff Controller
User Manual
Copyright – MoTeC Pty Ltd – 2001-2007
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.
6 June, 2007
Contents
Introduction.........................................................................1
MDC Functionality ..............................................................2
Mode selection ................................................................................................... 2
Lock Calculation ................................................................................................. 2
Slip Control......................................................................................................... 3
Slip control example................................................................................ 3
Speed Measurement .......................................................................................... 4
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
User CAN Bus......................................................................................... 5
ECU Comms Bus .................................................................................... 5
Miscellaneous functions ..................................................................................... 6
Fault indication ........................................................................................ 6
ABS Active Detection .............................................................................. 6
MDC Manager......................................................................7
Computer requirements...................................................................................... 7
Connecting to a MDC ......................................................................................... 7
Installing MDC Manager ..................................................................................... 7
Managing Configurations ................................................................................... 7
Changing Configurations .................................................................................... 7
User Mode Tables................................................................................... 7
File | Setup | Input ................................................................................... 8
File | Setup | Output ................................................................................ 9
File | Setup | User Modes........................................................................ 9
Monitoring MDC Data ....................................................................................... 10
Sending Firmware ............................................................................................ 10
MDC Installation................................................................11
Appendices........................................................................12
Appendix A – Fault Codes................................................................................ 12
Appendix B – MDC Pinout and Links ............................................................... 13
MDC Connector Pinout ......................................................................... 13
Links...................................................................................................... 14
Appendix C – CAN Wiring Practices ................................................................ 15
Appendix D – ECU Communications ............................................................... 16
ECU Link Configuration ........................................................................ 16
Enabling ECU Communications............................................................ 16
Receiving MDC Data............................................................................. 16
Receiving ECU Data ............................................................................. 18
Appendix E – CAN Messages .......................................................................... 19
50Hz Messages .................................................................................... 19
25Hz Messages .................................................................................... 20
MoTeC MDC 1 Introduction
Introduction
The MoTeC Mitsubishi Diff Controller (MDC) is a direct replacement for the Active Centre Diff (ACD) controller in
the Mitsubishi EVO7 to EVO9.
The MDC also supports centre diff control on Active Yaw Control (AYC) equipped vehicles. However the yaw
control hardware is not used.
EVO4 and EVO5 are not supported as the AYC module in these vehicles uses a slightly different connector. These
vehicles could be rewired to suit the MDC, please contact MoTeC for details.
This manual covers the installation, configuration and functionality of the MDC.
MoTeC MDC 2 Functionality
MDC Functionality
Mode selection
There are six user selectable control modes, four of which are user configurable. The control modes can be cycled
though using the dash mounted ACD button in the sequence below. The current mode is indicated on the
TARMAC, GRAVEL and SNOW dash board lights as follows:
0% Lock User Mode 1 User Mode 2 User Mode 3 User Mode 4 Constant Lock
TARMAC
○ ○
○
●
●
●
GRAVEL
SNOW
Note: If the mode has not changed for one minute then the current mode is saved and will be used next time the
MDC 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 and ABS override 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)
Brake
OFF
ON
Slip
Calculation
(% lock)
+
100%
Lock
MIN
5%
Lock
OFF
ON
ABS
Lock
0%
Handbrake
OFF
ON
% lock
Slip
control
params
MoTeC MDC 3 Functionality
The lock percentage for the constant lock mode is determined according to the following strategy:
Constant
lock %
5%
Lock
The constant lock % is equivalent to the maximum lock achieved by the Mitsubishi factory AYC / ACD controller.
The lock percentage for the 0% lock mode is determined according to the following strategy:
0%
Lock
5%
Lock
ABS
OFF
ON
Note: ABS input functionality is turned off by default and normally not required.
Note: The handbrake status is ignored during a handbrake start from 0km/h – See Handbrake Override below.
OFF
ON
ABS
0%
Lock
% lock
Handbrake
OFF
ON
% lock
For information on configuring the user modes see the MDC Manager section.
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 MDC Manager section.
MoTeC MDC 4 Functionality
Speed Measurement
The four wheel speed sensors are either directly connected to the MDC, or via the ABS module (if fitted). If the
ABS module is removed, the sensors must be directly connected to the MDC.
The MDC wheel speed inputs can be configured as hall effect or magnetic sensors with adjustable thresholds, and
individual sensors can be enabled or disabled. The speed calibration can be adjusted for different wheel sizes and
sensor teeth. Magnetic sensor input thresholds are individually configurable for front and rear sensor pairs
according to the current front and rear speeds.
Front, rear and vehicle speeds are calculated from the wheel speeds, and all speeds are transmitted in CAN
messages for logging by the ADL (Advanced Dash Logger).
Individual wheel speeds are transmitted to the ECU over a communication bus using factory wiring. A MoTeC
EVO89 or EVO48 OEM ECU (if fitted) can be configured to log these wheel speeds or use them in engine control
strategies.
For information on configuring speed inputs, see Setup | Input in the MDC 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 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 MDC Manager configuration program allows throttle input voltages to be read directly from the MDC in order
to perform 0% and 100% calibrations.
For information on calibrating the throttle input, see Setup | Input in the MDC Manager section.
Steering Position Measurement
The steering position sensor is a rotary encoder that has an index output to indicate the 0° rotation position. The
steering wheel position will be reported as 0° until it has passed the 0° rotation position and an absolute position is
known.
MoTeC MDC 5 Functionality
Note: if the MDC is powered up with the steering at full lock it will read +/-360deg when the wheels are straight.
This is a characteristic of the steering sensor which will be automatically corrected when the vehicle starts moving,
through analysis of steering angle, vehicle speed and lateral G force.
Hydraulic Pressure Pump Control
The MDC reads the hydraulic pressure sensor and controls the pump to maintain hydraulic pressure for the ACD.
The MDC implements the following strategies to protect the pump from being overrun and burnt out:
• If the pressure sensor is faulty or missing then the pump is turned off and remains off until the pressure
sensor reads a valid reading.
• If the pump has run for more than 20 seconds without achieving at least the low pressure threshold, the
pump is turned off for 20 seconds and a fault is indicated by a flashing mode indicator light.
• The pump will never run when the 0% lock mode has been selected
Hydraulic Pressure Pump Priming Mode
The hydraulic pressure pump priming mode allows the pump to be run manually by a technician during priming of
the hydraulic system.
To enter the pump priming mode, the ACD button should be pressed while turning on the ignition, and then remain
held pressed for five seconds. The SNOW and TARMAC lights on the dash will toggle when the priming mode is
active.
When priming mode is active, the diff lock is set at 50% and the hydraulic pump is run while the throttle pedal is
pressed down.
To exit the pump priming mode, the ignition should be turned off.
NOTE: The pump prime mode should be used with care by experienced technicians only. The MDC does NOT
restrict pump run time or hydraulic pressure during pump prime mode.
Communications
User CAN Bus
The MDC can communicate with a MoTeC ADL or a PC over the 1Mbit/sec User CAN bus. The MDC is connected
to a CAN bus using a separate communications connector. This cable also provides the power required if the
MoTeC CAN cable is used to interface with a PC.
The MDC transmits CAN messages at 50Hz containing information about all input and output functions, such as
speed readings, diff currents etc.
The MDC transmits CAN messages at 25Hz containing diagnostic information such as fault flags, firmware
versions etc.
To configure an ADL to receive MDC messages, use the ‘MDC’ and ‘MDC Diagnostics’ communications templates
included with Dash Manager.
The transmission of CAN messages can be disabled. This feature may be used to prevent reverse engineering of
user control modes.
The CAN bus is also used for communication with a PC for configuration and upgrading firmware using the
MoTeC UTC (USB To CAN) adaptor or the MoTeC CAN cable.
See Appendix C – CAN Wiring Practices for recommended CAN wiring practices
ECU Comms Bus
The MDC can communicate with a MoTeC EVO89 or EVO48 OEM ECU over a half-duplex RS232 link using the
factory wiring loom.
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