Control Module: Description and Operation
EAT ECUThe EAT ECU operates the solenoid valves in the gearbox to provide automatic control of gear shifts and torque converter lock-up. The EAT ECU is attached to a bracket which is secured to the cabin floor below the LH front seat.
Diesel vehicles from 95MY and petrol vehicles up to 99MY
A 55 pin connector links the EAT ECU to the vehicle wiring. Software in the ECU monitors hard wired inputs and exchanges information via hard wired connections with the ECM, BeCM and instrument pack.
Petrol vehicles from 99MY
A 75 pin connector links the EAT ECU to the vehicle wiring. Software in the EAT ECU monitors hard wired inputs and exchanges information with the ECM on a Controller Area Network (CAN) bus to determine gear shift and torque converter lock-up requirements. Resultant control signals are then output to the gearbox solenoid valves.
The CAN bus, introduced on 99MY petrol vehicles, provides the communication link between the ECM and the EAT ECU. Inputs and outputs to and from each control unit are transmitted via two twisted wire connections, CAN high and CAN low.
The CAN bus allows more engine data to be passed to the EAT ECU which, on earlier vehicles, would require a number of additional hardwired connections.
The additional engine data is used by the EAT ECU to give improved transmission quality and allows the EAT ECU to operate in a greater number of default modes in the event of sensor failure. Inputs and outputs on the CAN communication bus are listed in the table that follows.
CAN communications between EAT ECU and ECM - Petrol vehicles from 99MY