Jaguar XJ (X350). Manual — part 1042

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Pressure regulator 3

10

Pressure regulator 2

11

Pressure regulator 1

12

Discharge port

13

Suction port

14

Turbine speed sensor

15

Main control valve body

Transmission Electronic System

The transmission control module (TCM) and its input/output network control the following

transmission operations:

shift timing.

line pressure (shift feel).

torque converter clutch.

In addition, the TCM receives input signals from certain transmission-related sensors and switches.

The TCM also uses these signals when determining transmission operating strategy.

Using all of these input signals, the TCM can determine when the time and conditions are right for a

shift, or when to apply or release the torque converter clutch. It will also determine the pressure

needed to optimize shift feel. To accomplish this the TCM uses six pressure control solenoids and one

shift solenoid to control transmission operation.

The following provides a brief description of each of the sensors and actuators used to control

transmission operation.

TCM

The TCM for the transmission is mounted on top of the main control valve body. The control module

for the transmission has been designed to operate correctly in the environment in which the TCM is

located.

The transmission control module is activated and deactivated by the ignition supply and is connected

to the transmission link harness by a 16-way connector.

The TCM controls the operation of the transmission. The TCM processes information received in both

analogue and digital form such as:

Transmission input speed

Output speed

Throttle pedal position

Gear selector position

Engine torque

Engine speed

Transmission fluid temperature

Brake pedal status

Engine oil temperature

Coolant temperature

ABS wheel speed

This information is then used by the TCM to decide which shift pattern to select and for shift energy

management. Electro-hydraulic solenoid valves and pressure regulators control the transmission gear

changes.

Five pressure regulators and one solenoid valve are used to control direct transmission fluid flow to

select internal clutches and control the fluid pressure at the clutch. A separate pressure regulator is

used exclusively for torque converter clutch control.

The TCM monitors all TCM inputs and outputs to confirm correct system operation. If a fault occurs

the TCM is able to perform default action and inform the driver of the problem, this is by the

instrument cluster message centre.

Solenoids

The hydraulic module contains one solenoid valve. The solenoid valve is actuated by the TCM and has

two positions of open or closed, it is used to switch the position valve.

There are six electronic pressure control valves, these convert an electric current into a proportional

hydraulic pressure. They are energized by the TCM and actuate the valves belonging to the relevant

switching elements.

Controller Area Network (CAN) Interface

For the TCM to be able to perform shift point and shift quality management a number of external

signals are required. For shift point management alone the TCM requires output speed sensor,

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throttle pedal position, brake pedal status and gear selector position. The controller area network

(CAN) bus is used to share information between control modules. The TCM obtains most of its

required data over the CAN bus from the electronic engine controls, J-Gate and ABS, Instruments

pack and diagnostic tools.

Brake Pedal Position (BPP) Switch

The brake pedal position (BPP) switch tells the TCM when the brakes are applied, and disengages

torque converter clutch. The BPP switch closes when the brakes are applied and opens when they

are released. The BPP is also used to disengage the brake shift interlock and stops gradient

calculations.

Engine Coolant Temperature (ECT) Sensor

The engine coolant temperature (ECT) sensor detects engine coolant temperature and supplies the

information to the TCM. The ECT sensor is used to control the torque converter clutch (TCC)

operation.

Accelerator Pedal Position (APP) Sensor

The accelerator pedal position (APP) sensor is a potentiometer mounted on the accelerator pedal.

The APP sensor detects the position of the accelerator pedal and sends this information to the

electronic control module (ECM). The APP sensor is used for shift scheduling and TCC lock-up.

Input Shaft Speed (ISS) Sensor

The input shaft speed (ISS) sensor is a Hall effect type sensor.

The ISS sensor is mounted internally on the transmission and is located on the TCM and main control

valve body unit.

Output Shaft Speed (OSS) Sensor

The output shaft speed (OSS) sensor is a Hall effect type sensor.

The OSS sensor is mounted internally on the transmission and is located on the TCM and main

control valve body unit and is used for shift scheduling.

Transmission Fluid Temperature (TFT) Sensor

The TCM utilizes one transmission fluid temperature sensor located on the main control valve body.

The TCM uses the sensor input to activate various shift strategies. The sensor is in the form of a

temperature dependent resistor.

The temperature sensor performs plausibility checks on each sensor reading. Obviously, the

transmission oil temperature should not jump in value excessively between sensor readings. If the

inputs from the temperature sensor are outside the working range it possible that the sensor is short

or open circuit.

Position sensor

The TCM uses the position of this switch housed on the TCM and main control valve body, to

determine the selected gear range on the Automatic side of the selector lever.

The selector lever is connected to the transmission by a cable, which operates the transmission

selector shaft between positions Park, Reverse, Neutral and Drive. The TCM detects the driver's

choice of manual range selection (5,4,3,2) by means of a 3-bit code generated by the J-gate. This 3-

bit code is then transformed in to a CAN message by the J-Gate module and transmitted on to the

CAN bus where it is detected by the TCM.

3-Bit Code

Position

3-Bit Code

2nd Gear 0

1

0

3rd Gear

0

1

1

4th Gear

1

0

0

5th Gear

1

0

1

P, R, N, D 1

1

1

The TCM uses this information to generate the CAN message "Gear Position Selected", which must

not be confused with the similar message "Gear Position Actual" indicating the current mechanical

gear ratio activated by the TCM.

Movement of the lever between Park, Reverse, Neutral and Drive manually controls the flow of

transmission fluid, the TCM having control of the forward gear selected in Drive. Additional

movement of the lever to 5,4,3 and 2 positions does not manually modify the fluid flow, the TCM

detects these positions, and controls the gear selected electronically.

Sport mode switch

The sport mode switch:

Allows the driver to select or de-select the automatic transmission sport mode.

Allows the automatic transmission to operate normally when the sport mode is selected, but

under acceleration the gear shift points are extended to make full use of the engine's power
reserves.

Allows the driver to drive the vehicle in the "D" position with the full automatic transmission shift

or manually shift gears in the "second, third, fourth and fifth" positions.

Is illuminated when Sport mode is selected.

Communicates with the TCM through the CAN network to show the sport mode switch status.

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