Part 3
Four-Wheel Drive Systems 'Continued'TRANSFER BOX CONTROL MODULE OUTPUTS
The transfer box control module sends the following outputs:
^ CAN bus messages
^ Key interlock solenoid
^ High/low range change LED
^ Transfer box motor
^ Solenoid.
CAN Bus Messages
The control module also sends messages via the CAN bus to tell other control modules on the network, the status of the transfer box. The high/low status, clutch torque and default mode status are some of the main signals sent out by the transfer box control module.
Key Interlock Solenoid
The transfer box control module is able to send a signal to the key interlock solenoid. This signal locks the key in the ignition barrel to prevent it from being removed if the transmission is not in the 'Park' position.
High/Low Range Change LED
The control module is responsible for illuminating the 2 'high/low' range change LED's adjacent to the range change lever. One LED indicates high range and the other indicates low range.
One LED will be on continuously when in the corresponding range.
When changing range, the current range LED will remain on until the new range status has been achieved.
The new range LED will start flashing only when the range change has commenced (i.e. speed and neutral conditions have been met). The new range LED will be illuminated continuously at the same instant that the current range (now the old range) LED turns off.
The flash rate is 2 Hz with a 50% duty cycle.
The LED's have 2 levels of intensity, high when the vehicle lights are switch off and low when they are switched on.
If both lights are flashing at 0.5 Hz, this would indicate a transfer box fault or that the transfer box is in undefined range and may require calibration.
Transfer Box Motor
The transfer box motor provides the necessary movement to perform the high/low range change and the multi-plate clutch actuation. The motor is located on the rear casing assembly and secured with four bolts.
The motor is a PWM controlled, DC motor with an integrated worm gear reduction drive. It is connected to the transfer box control module with an eight-pin connector; the power supply of the motor is maintained through two large diameter cables on the motor connector. An internal position sensor checks the rotational movement of the motor.
There is a temperature sensor located within the motor housing.
Solenoid
The solenoid switches the power flow on the actuation system between high/low range change mode and clutch control mode. When the solenoid is energized, the solenoid pin deploys and activates the clutch control mode. When the solenoid is de-energized, the internal spring rejects the solenoid pin and activates the high/low range change mode.
NOTE: In order to replace the solenoid in service, the solenoid must be energized using T4.
The solenoid is connected to the transfer box control module with a two-pin connector.
Status Indication
Instrument Cluster
The low range status indicator will take the form of a mountain symbol and has the following logic:
^ Lamp on = low range
^ Lamp off = high range
^ Lamp flashing = range change in progress/range undefined/range fault.
There will also be a message displayed in the message center, which will inform the driver of any faults with the transfer box.
The following table shows the messages that can be displayed in the message center relating to the transfer box:
SERVICE
Basic Dimensions (Millimeters)
The transfer box weighs 40.30 kg without oil and 41.55 kg with oil. The unit requires 1500 ml ± 2% of oil from empty (dry).
The oil used in the transfer box is Shell TF 0753, which has been specially developed by Magna Steyr and Shell. The oil contains unique additives, which enhance the transfer box operation. No other oil must be used in the transfer box.
There is a unique type of grease, Weicon anti-seize montagepaste grau TL 7391, that needs to be applied to the units input shaft spline when installing or reinstalling the transfer box.
DIAGNOSTICS
The transfer box control module can store fault codes, which can be retrieved using T4 or a diagnostic tool using KW2000* protocol.
The information is communicated via a diagnostic socket.
The diagnostic socket allows the exchange of information between the various control modules on the bus systems and T4 or another suitable diagnostic tool. The information is communicated to the socket via the CAN bus. This allows the retrieval of diagnostic information and programming of certain functions using T4 or another suitable diagnostic tool.
The transfer box control module uses Diagnostic Trouble Codes (DTC), which relate to transfer box electrical faults.
Clutch and Range Change Mechanism Calibration
In order for the range change mechanism to function correctly, the transfer box control module must be calibrated to the mechanical dimensions of the transfer box that it is connected to.
This procedure will need to be followed if one of the following occurs:
^ The vehicle is first assembled
^ The switch is changed
^ The transfer box control module is changed
^ The transfer box or range position sensor is changed
^ Vehicle or transfer box control module fault has caused the transfer box to revert to an undefined range.
Calibration can be carried out using the service tool or by following this procedure:
^ Switch ignition to position 11 without the engine running
^ Select neutral
^ Depress the throttle pedal fully
^ Press and hold the range change switch for 5 or more seconds to allow calibration to start
^ When the calibration is heard to start, the switch and throttle pedal can be released
^ Upon adopting high range, start the engine and wait 30 seconds while the first calibration of the clutch in high range is done. While this calibration process is in progress, no shifting is accepted
^ Switch ignition off and wait 15 seconds
^ Start engine
^ Perform a range change to low range. Wait 30 seconds while the first calibration of the clutch in low range is done. While this calibration process is in progress, no shifting is accepted
^ Switch ignition off and wait 15 seconds
^ Range and clutch calibration is now complete.
SYSTEM OPERATION
The selection of high/low range is achieved by using a switch located behind the main transmission selection lever in the center console. A range change can only be performed when the transmission selector lever is in neutral (position 'N'). The accelerator pedal must not be depressed when a range change is in progress.
If high or low range is requested and the transmission selector lever is in a position other than 'N' or 'P', the instrument cluster message center will display 'SELECT NEUTRAL'.
NOTE: If the transmission selector lever is in the 'P' position, the range change will not take place and the 'SELECT NEUTRAL' message will not be displayed in the message center.
When low range is selected, the low range 'mountain' symbol will flash when the range change is taking place and then remain illuminated when the range change is complete. The instrument cluster message center will display 'LOW RANGE' for approximately 3 seconds followed by a chime from the instrument cluster to confirm that the range change has been completed. Only 'D' and 'Manual mode' are available, the 'Sport mode' selection is not available.
When high range is selected, the low range 'mountain' symbol will flash when the range change is taking place and then extinguish when the range change is complete. The instrument cluster message center will display 'HIGH RANGE' for approximately 3 seconds followed by a chime from the instrument cluster to confirm that the range change has been completed.
The design of the transfer box allows range changes when the vehicle is moving, within set limitations as follows:
^ High to Low - at speeds not exceeding 25 mph (40 km/h)
^ Low to High - at speeds not exceeding 37 mph (60 km/h).
If the vehicle speed is higher than the parameters given, the instrument cluster message center will display 'SLOW DOWN'. When the correct speed range is reached, the message will be deleted and the range change will commence.
The transfer box control module interprets a road speed of less than 2 mph (3 km/h) as a static shift (vehicle not moving). In this instance, the driver must use the shift lock procedure of operating the brake pedal to allow the selector lever to be moved from 'N' to 'D' after the range change has been performed.
High range should be used for all normal road driving and also for off-road driving across dry, level terrain. Low range should only be required where low speed maneuvering is necessary, such as reversing a trailer, negotiating steep slippery surfaces or boulder-strewn terrain. Low range should also be used for extreme off-road conditions where progress in high range cannot be maintained. Low range should never be used for normal road driving.
Terrain Response
The Terrain Response system allows the driver to select a program, which will provide the optimum settings for traction and performance for the prevailing terrain conditions.
The system is controlled by a rotary control located on the center console. The rotary control allows the selection of one of the following five programs:
^ Special programs off (general driving conditions)
^ Grass/Gravel/Snow
^ Mud/Ruts
^ Sand
^ Rock crawl.
The Terrain Response system uses a combination of vehicle subsystems to achieve the required vehicle characteristics for the terrain selected. The following subsystems form the Terrain Response system:
^ Engine management system
^ Transmission
^ Transfer box
^ Rear locking differential (if fitted)
^ Brake system
^ Air suspension.
Each subsystem control module provides a feedback for the selected program so that the Terrain Response control module can check that all systems are controlling the system correctly.
HIGH RANGE OPERATION
In high range, the torque input from the transmission is passed to the transfer box input shaft. The position of the synchronizer sleeve couples the shaft directly to the differential housing. The differential splits the torque between the two side gears. One side gear is connected by splines and passes the torque to the rear output flange. The second side gear is connected to the chain drive sprocket and passes the torque, via the chain, to the front output flange.
LOW RANGE OPERATION
In low range, the torque input from the transmission is passed to the transfer box input shaft. The synchronizer sleeve is moved and connects the planetary carrier to the differential housing. The torque from the transmission is now directed through the sun gear of the epicyclic gearset and, via the pinion gears and pinion gear shafts, into the planetary carrier. The annulus gear of the epicyclic gearset is secured inside the casing and generates the low range ratio of 2.93:1. The torque is then passed, via the synchronizer sleeve, to the differential housing where it is split between the two side gears. One side gear is connected by splines and passes the torque to the rear output flange. The second side gear is connected to the chain drive sprocket and passes the torque, via the chain, to the front output flange.
HIGH/LOW RANGE GEARS WITH SHIFT-ON-THE-MOVE
The driver is able to change between high and low range gears while the vehicle is moving, or if the vehicle is stationary.
Pushing the range change lever makes a range change requests. This lever is located on the center console behind and to one side of the main transmission lever.
The driver requests a high to low range change by pushing the range change lever towards the rear of the vehicle and, conversely, a low to high request by pushing the lever towards the front of the vehicle. The range change lever is center sprung and therefore does not latch in the forward or rear positions.
The driver is informed of the range status via a green lamp (mountain symbol) in the instrument cluster and LED's next to the range change lever. The lamp will not be illuminated in high range, illuminated in low range and flashes during a range change. There are two LED's on the range change lever one for high and one for low. During a range change the new range LED will flash.
The vehicle will remain in the selected range unless the driver requests a change, i.e. it will not automatically revert to high range following a key off/key on sequence.
RANGE CHANGE PROCEDURE
Neutral must be selected on the main transmission before requesting a range change and then select the appropriate gear following completion of the range change. During the range change the main transmission will be locked in neutral.
If neutral is not selected when a range change is requested then the request is denied and the driver will be advised to select neutral via the instrument cluster message center.
The range change process can take up to one second to complete following a request being accepted.
There is a limit set on the maximum speed at which a range change can be achieved. The maximum speed for a high to low range change is 25 mph (40 km/h). The maximum speed for a low to high range change is 37 mph (60 km/h). If the vehicle speed is over the limit when a range change is selected then the request is denied and the instrument cluster message center will display a 'SLOW DOWN' message.
TRANSFER BOX CONTROL DIAGRAM
NOTE: A = Hardwired; D = CAN bus
