Part 3
Automatic Transmission 'Continued'Power Flow 2nd Gear
The gear selector lever and the manual selector spool valve are in the 'D' position. Engine torque is transmitted from the torque converter turbine shaft to the ring gear 1 of the single web planetary gear train and the outer plate carrier of clutch 'E'.
Ring gear 1 drives the planetary gears which rotate around sunwheel 1. This drives the planetary gear carrier 1 and also the outer plate carrier of clutch 'A' and the inner plate carrier of clutch 'B'
When clutch 'A' is engaged, sunwheel 3 in the double web planetary gear train is driven and meshes with the short planetary gears.
Sunwheel 2 is locked to the transmission housing by brake clutch 'C'. The long planetary gears, which are also meshed with the short planetary gears, roll around the fixed sunwheel 2 and transmit drive to the double web planetary gear train carrier and ring gear 2 in the direction of engine rotation.
NOTE: Refer to 'Shift Elements' illustration for key
Power Flow 3rd Gear
The gear selector lever and the manual selector spool valve are in the 'D' position. Engine torque is transmitted from the torque converter turbine shaft to the ring gear 1 of the single web planetary gear train and the outer plate carrier of clutch 'E'.
Ring gear 1 drives the planetary gears which rotate around sunwheel 1. This drives the planetary gear carrier 1 and also the outer plate carrier of clutch 'A' and the inner plate carrier of clutch 'B'
When clutch 'A' is engaged, sunwheel 3 in the double web planetary gear train is driven and meshes with the short planetary gears.
Sunwheel 2 is driven via clutch 'B' which is engaged. The long planetary gears, which are also meshed with the short planetary gears, cannot roll around the fixed sunwheel 2 and transmit drive to the locked double web planetary gear train carrier in the direction of engine rotation.
NOTE: Refer to 'Shift Elements' illustration for key
Power Flow 4th Gear
The gear selector lever and the manual selector spool valve are in the 'D' position. Engine torque is transmitted from the torque converter turbine shaft to ring gear 1 of the single web planetary gear train and the outer plate carrier of clutch 'E'.
Ring gear 1 drives the planetary gears which rotate around sunwheel 1. This drives the planetary gear carrier 1 and also the outer plate carrier of clutch 'A' and the inner plate carrier of clutch 'B'
When clutch 'A' is engaged, sunwheel 3 in the double web planetary gear train is driven and meshes with the short planetary gears.
The double web planetary gear carrier is driven via clutch 'E' which is engaged. The long planetary gears, which are also meshed with the short planetary gears, and the double web planetary gear carrier, drive ring gear 2 in the direction of engine rotation.
NOTE: Refer to 'Shift Elements' illustration for key
Power Flow 5th Gear
The gear selector lever and the manual selector spool valve are in the 'D' position. Engine torque is transmitted from the torque converter turbine shaft to ring gear 1 of the single web planetary gear train and the outer plate carrier of clutch 'E'.
Ring gear 1 drives the planetary gears which rotate around sunwheel 1. This drives the planetary gear carrier 1 and also the outer plate carrier of clutch 'A' and the inner plate carrier of clutch 'B'
When clutch 'A' is engaged, sunwheel 3 in the double web planetary gear train is driven and meshes with the short planetary gears.
The long planetary gears, which are also meshed with the short planetary gears, and the double web planetary gear carrier, drive ring gear 2 in the direction of engine rotation.
NOTE: Refer to 'Shift Elements' illustration for key
Power Flow 6th Gear
The gear selector lever and the manual selector spool valve are in the 'D' position. Engine torque is transmitted from the torque converter turbine shaft to ring gear 1 of the single web planetary gear train and the outer plate carrier of clutch 'E'.
Clutches 'A' and 'B' are released, removing the effect of the single web planetary gear train.
Clutch brake 'C' is applied which locks sunwheel 2 to the transmission housing.
Clutch 'E' is engaged and drives the double web planetary gear carrier. This causes the long planetary gears to rotate around the fixed sunwheel 2 and transmit drive to ring gear 2 which is driven in the direction of engine rotation.
NOTE: Refer to 'Shift Elements' illustration for key
Power Flow Reverse Gear
The gear selector lever and the manual selector spool valve are in the 'R' position. Engine torque is transmitted from the torque converter turbine shaft to ring gear 1 of the single web planetary gear train and the outer plate carrier of clutch 'E'.
Ring gear 1 drives the planetary gears of the single web planetary gear train which rotate around the fixed sunwheel 1. This transmits the drive to the single web planetary gear carrier, the outer plate carrier of clutch 'A' and the inner plate carrier of clutch 'B'
With clutch 'B' applied, sunwheel 2 in the double web planetary gear train is driven and meshes with the long planetary gears.
The double web planetary gear carrier is locked to the transmission housing by brake clutch U. This allows ring gear 2 to be driven in the opposite direction to engine rotation by the long planetary gears.
NOTE: Refer to 'Shift Elements' illustration for key
CONTROL DIAGRAM
NOTE: A = Hardwired; D= High Speed CAN Bus
SELECTOR POSITION SWITCH
The Mechatronic valve block contains a position switch which is mechanically connected to the selector spool valve. The selector spool valve is connected by a selector shaft to the selector lever via a 'Bowden' selector cable.
The signals from the position switch are used by the TCM to determine the P, R, N or D selection made by the driver.
INSTRUMENT CLUSTER
The instrument cluster is connected to the TCM via the high speed CAN bus. Transmission status is transmitted by the TCM and displayed to the driver in one of two displays in the instrument cluster.
Malfunction Indicator Lamp (MIL)
The MIL is located in the tachometer in the instrument cluster. Transmission related faults which may affect the vehicle emissions output will illuminate the MIL.
The MIL is illuminated by the ECM on receipt of a relevant fault message from the TCM on the high speed CAN. The nature of the fault can be diagnosed using a Land Rover approved diagnostic system which reads the fault codes stored in the TCM memory.
Transmission Status Display
The transmission status display is located in a Liquid Crystal Display (LCD) within the speedometer housing. The LCD shows the selector lever position and the selected transmission mode. When the selector lever is in the manual CommandShiftTM position, the selector lever position display will show the selected gear ratio.
The following table shows the displays and their descriptions.
Message center Display
The message center is located in the lower center of the instrument cluster. The message center is a LCD to relay vehicle status and operating information to the driver. The message center can display messages relating to a number of the vehicle systems. The following list shows the possible transmission related messages:
^ TRANSMISSION FAULT LIMITED GEARS AVAILABLE
^ TRANSMISSION FAULT AND OVERHEAT
^ TRANSMISSION FAULT
^ TRANSMISSION OVERHEAT
TRANSMISSION CONTROL MODULE (TCM)
The TCM is an integral part of the Mechatronic valve block which is located at the bottom of the transmission, within the fluid pan. The TCM is the main controlling component of the transmission.
The TCM processes signals from the transmission speed and temperature sensors, engine control module and other vehicle systems. From the received signal inputs and pre-programmed data, the module calculates the correct gear, torque converter clutch setting and optimum pressure settings for gear shift and lock-up clutch control.
The TCM outputs signals to control the shift control solenoid valve and the Electronic Pressure Regulator Solenoids (EPRS) to control the hydraulic operation of the transmission.
The ECM supplies the engine management data on the high speed CAN bus system. The TCM requires engine data to efficiently control the transmission operation, for example; flywheel torque, engine speed, accelerator pedal angle, engine temperature etc.
The steering angle sensor and the ABS module also supply data to the TCM on the high speed CAN bus system. The TCM uses data from these systems to suspend gear changes when the vehicle is cornering and/or the ABS module is controlling braking or traction control.
The selector lever is connected to the automatic transmission and the position switch in the transmission by a Bowden cable. Movement of the selector lever moves the position switch via the Bowden cable and the switch position informs the TCM of the selected position. The sport/manual ± CommandShift switch passes manual/sport selections to the TCM. An additional switch provides a selector lever in park position signal. Once the selector lever position is confirmed, the TCM outputs appropriate information which is received by the instrument cluster to display the gear selection information in the message center.
The Mechatronic valve block also contains the speed and temperature sensors. These are integral with the Mechatronic valve block and cannot be serviced individually. The speed sensors measure the transmission input and output speeds and pass signals to the TCM. The fluid temperature sensor is also located in the valve block and measures the fluid temperature of the transmission fluid in the fluid pan.
The TCM is connected to the starter relay coil. When the selector lever is in PARK or NEUTRAL, the module provides a ground for the coil allowing the starter relay to be energized and allow starter motor operation. If the selector lever is in any other position, the module will not provide the ground preventing starter motor operation.
DIAGNOSTICS
The diagnostic socket is located in the lower instrument panel closing panel, on the driver's side, below the steering column.
The diagnostic socket allows the exchange of information between the various modules on the bus systems and a Land Rover approved diagnostic system or a diagnostic tool using IS01 4229 protocol. The information is communicated to the socket via the high speed CAN bus from the TCM. This allows the retrieval of diagnostic information and programming of certain functions using a Land Rover approved diagnostic system or a suitable diagnostic tool.
CONTROLLER AREA NETWORK (CAN)
The high speed CAN broadcast bus network is used to connect the powertrain modules. The CAN bus is connected between the following electronic units:
High Speed CAN Bus
^ TCM
^ Instrument cluster
^ Air suspension module
^ Steering angle sensor
^ Rear differential module
^ center console switch pack
^ Electric park brake module
^ Restraints control module
^ Engine Control Module (ECM)
^ ABS module
^ Adaptive front lighting control module
^ Transfer box control module
^ Adaptive cruise control module
^ Diagnostic socket.
The CAN bus allows a fast exchange of data between modules. The CAN bus comprises two wires which are identified as CAN high (H) and CAN low (L). The two wires are colored yellow/black (H) and yellow/brown (L) and are twisted together to minimize electromagnetic interference (noise) produced by the CAN bus messages.
In the event of CAN bus failure, the following symptoms may be observed:
^ Transmission operates in default mode
^ Torque converter lock-up clutch control is disabled
^ Gear position indication in instrument cluster message center inoperative (this will also occur with any transmission fault).
DRIVING MODES
There are a number of different driving modes of operation. Some can be selected by the driver and some are automatically initiated by the TCM during driving:
^ Normal mode
^ Sport mode
^ Manual (CommandShiftTM) mode
^ Adaptive Shift Strategy (ASIS)
^ Hill Descent Control (HDC) mode
^ Cruise mode
^ Hill mode
^ Default (Limp home) mode
^ Reverse lock-out mode
^ Cooling strategy.
^ Curve recognition mode
^ Fast off recognition
Normal Mode
Normal mode is automatically selected by the TCM on power up. In this mode all automatic and adaptive modes are active. Normal mode uses gear shift and lock-up maps to allow for vehicle operation which offers fuel consumption and emissions or driveability depending on the driving style. If the transmission is operated in sport or manual mode and the selector lever is moved to the 'D' position, normal mode is automatically resumed.
Sport Mode
Sport mode operates in high range only and provides enhanced acceleration and responsiveness. In sport mode the TCM uses shift maps which allow the transmission to downshift more readily, hold gears for longer at higher engine speeds, and limits the transmission to the first five gears (6th gear is not used).
Sport mode is selected by moving the selector lever to the left into the 'M/S' position. When the sport mode is first selected, 'SPORT' is displayed in the message center for 6 seconds and, if 6th gear is currently engaged, the TCM downshifts to 5th.