Freelander System Description and Operation
AUTOMATIC GEARBOX - JATCO
44-34
DESCRIPTION AND OPERATION
Electronic Automatic Transmission (EAT) ECU
The EAT ECU is located in the Environmental box (E-box) in the engine compartment, adjacent to the ECM. The ECU
is connected to the vehicle wiring by a 54 pin connector (C0932).
The EAT ECU uses a 'flash' Electronic Erasable Programmable Read Only Memory (EEPROM). This enables a new
or replacement EAT ECU to be externally configured. EEPROM also allows the EAT ECU to be updated with new
information and market specific data.
To input new information and market specific data the EAT ECU must be configured using TestBook/T4. The
EEPROM allows the ECU to be reconfigured as many times as necessary to meet changing specifications and
legislation.
The EAT ECU memorises the signal values of the gearbox sensors and actuators. These stored values ensure
optimum gearbox performance is achieved at all times.
This information is lost if battery voltage is too low, for example if the battery becomes discharged. The EAT ECU
reverts to default readings on first engine start after a battery discharge or disconnection. The EEPROM facility in the
ECU allows the stored values to be re-learnt, ensuring optimum gearbox performance.
If these signals are not within the EAT ECU stored parameters, the ECU will make adjustments to the operation of the
gearbox through the actuators to provide optimum driveability and performance.
The inputs from the sensors constantly updates the EAT ECU with the current operating condition of both the gearbox
and the engine. The ECU compares this current information with mapped information stored within its memory. The
ECU will make any required adjustment to the operation of the gearbox through the following actuators:
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Gear control solenoid valves
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Lock-up solenoid valve
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Line pressure solenoid valve.
The EAT ECU also interfaces with the following:
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Engine Control Module (ECM) via the CAN
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Instrument pack via the CAN
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Diagnostic socket via the ISO 9141 K line.
