Controller Area Network (CAN) system
The CAN system is a high speed serial interface between the ECM and the Electronic Automatic Transmission (EAT)
ECU. The CAN system uses a data bus to transmit information messages between the ECM and the EAT ECU.
Because there are only two components in this CAN system, one will transmit information messages and the other
will receive information messages, and vice-versa.
The CAN system is used by the EAT ECU and the ECM for the following:
l Gearshift torque control information.
l EAT OBD information.
l MIL request.
l Vehicle speed signal.
l Engine temperature.
l Engine torque and speed.
l Gear selected.
l Gear change information.
The CAN system uses a twisted pair of wires to form the data bus to minimise electrical interference. This method of
serial interface is very reliable and very fast. The information messages are structured so that each of the receivers
(ECM or EAT ECU) is able to interpret and react to the messages sent.
The CAN data bus is connected directly between pin 32 of connector C0158 of the ECM and pin 44 of connector
C0193 at the EAT ECU, and pin 35 of connector C0158 of the ECM and pin 16 of connector C0193 at the EAT ECU.
The CAN system can fail in the following ways:
l CAN data bus wiring open circuit.
l CAN data bus wiring short circuit.
In the event of a CAN data bus failure any of the following symptoms may be observed:
l EAT defaults to reverse and 4th gear if the vehicle is moving, 3rd gear if the vehicle is stationary.
l Harsh gearshifts.
l Sport and manual warning lamps flash alternately.
