Part 2

Transmission Description

Powerflow Schematic









Engine torque is transferred, via operation of single or combinations of clutches to the 2 planetary gear trains. Both gear trains are controlled by reactionary inputs from brake clutches to produce the 6 forward gears and 1 reverse gear. The ratios are as follows:





The following table shows which solenoids are activated to produce the required torque output from the transmission.





The following table shows which clutches are operating for selected gear ratios to produce the required torque output from the transmission.





Shift Elements









The shift elements are 3 rotating multiplate clutches (A, B and E) and 2 fixed multiplate brakes (C) and D). All shifts from 1st to 6th gears are power-on overlapping shifts. Overlapping shifts can be described as one of the clutches continuing to transmit drive at a lower main pressure until the next required clutch is able to accept the input torque.
The shift elements, clutches and brakes are actuated hydraulically. Fluid pressure is applied to the required clutch and/or brake, pressing the plates together and allowing drive to be transmitted through the plates. The purpose of the shift elements is to perform power-on shifts with no interruption to traction and smooth transition between gear ratios.





Power Flow 1st Gear
The gear selector lever and the manual selector valve spool 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.
The double web planetary gear train is locked against the transmission housing by brake 'D'. This allows ring gear 2 (output shaft) to be driven in the same direction as the engine via the long planetary gears.

NOTE:
Refer to 'Shift Elements' illustration for key





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 'D'. 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





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 2 displays in the instrument cluster. For additional information, refer to Instrument Cluster Description and Operation

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 the Integrated Diagnostic System (IDS) 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) at the top of the instrument cluster, between the speedometer and the tachometer. The LCD shows the selector lever position or the selected gear when in manual 'Jaguar Sequential Shift' mode.
The following table shows the displays and their descriptions.





Message Centre Display
The message centre is located in the lower centre of the instrument cluster. The message centre is a LCD to relay vehicle status and operating information to the driver and can display messages relating to a number of the vehicle systems. If a transmission fault occurs, the message centre will display the message 'GEARBOX FAULT'.

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, ECM 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 cable and the switch position informs the TCM of the selected position. The sport switch passes the sport selection to the TCM. 'Jaguar Sequential Shift' selections are sensed when the driver operates the steering wheel paddle switches. An additional switch provides a selector lever 'not 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 centre.
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.
A 'not in park' switch is located in the selector lever mechanism. The switch is connected to the instrument cluster, Central Junction Box (CJB) and the ECM. The instrument cluster uses the park switch status to display the selector position. The ECM uses the status to allow starter motor operation only when the selector lever is in the Park or Neutral positions. The signal is also passed from the CJB to the TCM.

CONTROLLER AREA NETWORK (CAN)
The high speed CAN bus is used to connect the powertrain modules. The CAN bus is connected between the following electronic units:

High Speed CAN Bus
- TCM
- Instrument cluster
- Adaptive Damping Control Module (ADCM) - if fitted
- Steering angle sensor
- Electric park brake module
- Restraints control module
- Engine Control Module (ECM)
- ABS control module
- Adaptive front lighting control module - if fitted
- Adaptive cruise control module - if fitted
- Diagnostic socket.
The CAN bus allows a fast exchange of data between modules. The CAN bus comprises 2 wires which are identified as CAN high (H) and CAN low (L). The 2 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. For additional information, refer to Communications Network Description and Operation
In the event of CAN bus failure, the following symptoms may be observed:
- Transmission operates in default (limp home) mode
- Torque converter lock-up clutch control is disabled
- Gear position indication in instrument cluster message centre 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 ('Jaguar Sequential Shift') mode
- Adaptive Shift Strategy (ASIS)
- 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
The sport mode 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 across the 'L' gate into the 'S' position. When the sport mode is first selected, if 6th gear is currently engaged, the TCM downshifts to 5th.

Manual ('Jaguar Sequential Shift') Mode
Manual mode allows the transmission to operate as a semi-automatic 'Jaguar Sequential Shift' unit. The driver can change up and down the 6 forward gears with the freedom of a manual transmission.
Shift maps are provided for manual mode to protect the engine at high engine speeds. The TCM will automatically change up to a higher gear ratio to prevent engine overspeed and change down to a lower gear ratio to avoid engine laboring and stalling.
When kickdown is requested the TCM downshifts at least 2 gears.
When the vehicle is stationary, to drive off the driver can select 1st , 2nd or 3rd gear. Any other gear selection will be rejected by the TCM.
When driving off, upshifts can be pre-selected by making + selections with the appropriate steering wheel upshift or downshift paddle for the number of upshifts required. The TCM then automatically performs a corresponding number of upshifts when the appropriate shift points are reached. So, for example, when starting off in 1st gear, if three upshift (+) selections are made in quick succession, the TCM will automatically change up through the box to 4th gear as the vehicle accelerates, without any further selections being made.
In manual mode a low gear can be selected to provide engine braking for descending a slope or continuous use of the brake pedal. The driver can prepare for the end of the descent by moving the selector lever to D. The TCM will maintain the low gear and only revert to automatic shift control when the throttle is opened and vehicle speed increases.

Adaptive Shift Strategy (ASIS)
The ASIS system is a new feature on automatic transmissions. With the TCM linked via the CAN bus to other vehicle systems, signals are received which can allow the TCM to calculate the way in which the vehicle is being driven. The type of signals include the following:
- Longitudinal and lateral acceleration
- Engine speed
- Engine torque
- Oil temperature
- Accelerator pedal position
- Wheel speed.
Using these signals, additional transmission control can be obtained. The TCM can calculate when the vehicle is cornering, all wheels are gripping, the driver is braking or if the driver is accelerating. This is the conventional 'Adaptive' transmission control. ASIS uses this system but adds the continuous adaptation of the gear changes to suit the individual driving style of the driver.

Cruise Mode
When speed control is activated, the TCM receives a cruise active message on the CAN bus. The TCM activates a speed control map which prevents locking and unlocking of the torque converter clutch and minimizes up and down shifts.

Hill Mode
Hill mode is initiated by the TCM when the engine torque, received via ECM signals on the CAN bus, exceeds the theoretical load curve for normal operation. The TCM monitors this signal to determine when the vehicle is travelling up or down a steep gradient.
In hill mode the TCM adopts one of four shift maps, three uphill and one downhill. The shift map chosen depends on the severity of the slope as determined from the engine signals and the appropriate gear is selected to assist with the ascent or descent.
Hill mode can also be initiated when the vehicle is at very high altitudes or ambient temperatures.

Default (Limp Home) Mode
If a transmission fault is detected by the TCM, the TCM adopts a limp home mode strategy. 'GEARBOX FAULT' is displayed in the message centre and, if the fault has an effect on engine emissions, the MIL will also be illuminated.
In default mode, P, R and N functions operate normally (if the fault allows these selections) and the TCM locks the transmission in 3rd or 5th gear to allow the driver to take the vehicle to the nearest dealer. The torque converter lock-up clutch is disabled and reverse lock-out will not function.
If the vehicle is stopped and subsequently restarted in the default mode condition, the TCM operates normally until the fault which caused the condition is detected again.
If electrical power is lost and the transmission is operating in mechanical limp home mode, the selector lever will be locked in the 'N' or 'P' position by the shift interlock solenoid if moved from the 'D' position.

Reverse Lock-Out Mode
When the vehicle is travelling forwards, selecting reverse could cause transmission damage. To protect against this, reverse gear is prohibited if the vehicle is travelling forwards at a road speed of 5 mph (8 km/h) or higher.

Cooling Strategy
The purpose of the cooling strategy is to reduce engine and transmission temperatures during high load conditions. Under these conditions the engine and transmission may generate excessive heat.
If the transmission fluid temperature increases to 125°C (257°F) or higher, the TCM employs the cooling strategy. No message is displayed in the message centre for transmission overheat.
The strategy uses a specific shift and torque converter lock-up clutch map. This map allows torque converter clutch lock-up and gear shifts to operate outside of their normal operation. This will reduce the engine speed and/or slip in the torque converter, therefore reducing heat generated by the engine and the transmission.
If the transmission fluid temperature increases to 137°C (278°F) or higher, the transmission will use the default (limp home mode). If the temperature exceeds 140°C (284°F), CAN bus transmission is disabled.
The cooling strategy is cancelled when the transmission fluid temperature decreases to less than 120°C (248°F) or below.

Curve Recognition
Curve recognition is activated when high levels of lateral acceleration and/or steering angle are detected via the ABS module and steering angle sensor signals on the CAN bus. When this condition is detected, the TCM prevents the transmission from changing to a higher gear to assist with cornering. When the vehicle completes it's manoeuvre, the transmission will shift to the correct ratio.

Fast Off Recognition
Fast off recognition is activated when the TCM detects that the driver has backed off the accelerator pedal quickly in a 'change of mind' manoeuvre. This is detected by monitoring for a high level of negative pedal angle from the engine control module signal on the CAN bus. If this condition is detected, the TCM holds the current gear ratio to allow the driver to complete his original action without the need for a downshift. The mode remains active for a predetermined time period or if the driving style remains passive.

TRANSMISSION FAULT STATUS
If the TCM detects a fault with the transmission system, it will enter a default mode to prevent further damage to the transmission and allow the vehicle to be driven.
When a fault is detected a CAN message is sent from the TCM and is received by the instrument cluster. The instrument cluster illuminates the MIL, if an emissions related fault occurs, and displays 'GEARBOX FAULT' in the message centre.
Some transmission faults may not illuminate the MIL or display a fault message, but the driver may notice a reduction in shift quality. For additional information, refer to Transmission Description Description and Operation

ENGINE SPEED AND TORQUE MONITORING
The ECM constantly supplies the TCM with information on engine speed and torque through messages on the CAN bus. The TCM uses this information to calculate the correct and appropriate timing of shift changes.
If the messages are not received by the ECM, the TCM will implement a back-up strategy to protect the transmission from damage and allow the vehicle to be driven.
In the event of an engine speed or torque signal failure, the transmission will adopt the electrical limp home mode with the transmission operating in a fixed gear.

TOWING FOR RECOVERY
The following procedure must be used to ensure that the vehicle is towed in a safe condition and damage to the vehicle transmission systems is prevented.
- Secure the towing attachment from the recovery vehicle to the towing eye of the vehicle to be recovered.
- Make sure that the parking brake is on. Press the start/stop button to switch the ignition on.
- Apply the footbrake and move the automatic transmission selector lever to the neutral position. If electrical power is not available, use the manual interlock release tab on the selector lever to move the lever to the neutral (N) position.
- Make sure that the Smart Key is placed in the start control module to ensure that the electric steering lock is disengaged and, if the stop lamps and turn signal indicators are required, the start/stop button is pressed and the ignition is on.
- Make sure that the parking brake is released before the vehicle is towed.
- The vehicle can only be towed for a maximum of 0.5 miles (0.8 km) at a maximum speed of 30 mph (48 km/h).

WARNING: Do not remove the Smart Key from the vehicle when the vehicle is being towed. The electric steering lock will be engaged preventing the steering from being turned.
With the engine not running, the brake booster and power steering pump will be inoperative. Care must be taken to ensure the vehicle is manoeuvred and driven accordingly.


CONTROL DIAGRAM

NOTE:
A = Hardwired; D = High speed CAN Bus; N = Medium speed CAN Bus