TSX L4-2.4L (2005)
input) are the receivers. For example, the Combination Switch Control Unit monitors the wiper switch. When the wiper switch is placed in the low speed
position, the Combination Switch Control Unit transmits that message on the communication circuit. The Relay Control Module receives the message
and turns on the wipers by providing a ground for the relay.
"Connected" ECUs
Several ECUs are connected to each of the two networks. The Gauge Control Module is part of both networks since it is the "Gateway" between them.
Below is a list of ECUs and the network they are connected to.
B-CAN ECUs
-
Gauge Control Module
-
Relay Control Module
-
Multiplex Integrated Control Unit (MICU)
-
Door Multiplex Control Unit
-
Combination Switch Control Unit
-
Climate Control Unit
F-CAN ECUs
-
Gauge Control Module
-
ECM/PCM
-
Navigation Control Unit
-
VSA (Vehicle Stability Assist)
Network "Loss of Communication" Error Checking
The B-CAN and F-CAN systems send messages to each other to check the integrity of the network communication circuit. They do this by sending a
specific digital message out after an event. For example, turning the ignition switch to ON. After the switch to ON, all the ECUs on the communication
circuit expect to receive a message from other specific units within a specified amount of time. If the message is not received, the ECU will transmit a
DTC reporting that the control units did not communicate.
Example of communication circuit test
Normal circuit
1. Ignition switch turned ON.
2. The door multiplex control unit transmits a door switch signal.
3. The multiplex integrated control unit (MICU), relay control module and gauge control module receive the door lock switch signal.
4. Communication circuit test is passed.
Since the door lock switch message was received by all the ECUs expecting to receive a signal, the communication circuit between those units is
OK. There are multiple signal sent and received by each ECU during this time to insure that the communication circuit is intact.
Failed circuit
5. Ignition switch is turned ON.
