Electronic Automatic Transmission (EAT) ECU (Automatic gearbox - Jatco)

The EAT ECU transmits the selector lever position through the CAN bus to the ECM. The ECM processes this information and passes it to the instrument pack in the form of CAN messages to display the gearbox status.

If the gearbox develops a fault and adopts the limp home mode, the LCD will alternately display 'F' and 4'' to alert the driver that a fault has occurred and limp home mode is operational.

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: l Gear control solenoid valves l Lock-up solenoid valve l Line pressure solenoid valve.

The EAT ECU also interfaces with the following: l Engine Control Module (ECM) via the CAN l Instrument pack via the CAN l Diagnostic socket via the ISO 9141 K line.