Body Controller Area Network (B-CAN) and Fast Controller Area Network (F-CAN)
Fast controller Area Network (F-CAN) and Body Controller Area Network (B-CAN) share information between multiple Electronic Control Units (ECUs). B-CAN communication moves at a slower speed for convenience related items, and for other functions. F-CAN information moves at a faster speed for "real time" functions such as fuel and emissions data. To allow both systems to share information, the Gauge Control Module translates information from B-CAN to F-CAN and from F-CAN to B-CAN.
The ECUs on the B-CAN and F-CAN transmit and receive information in the form of structured messages that may be received by several different ECUs on the network at one time. These message are transmitted and received across a communication circuit that consists of a single wire that is shared by all the ECUs on the circuit. Since messages on the F-CAN network are typically of higher importance, a second wire is used for communication circuit integrity monitoring. A backup circuit is also added to the headlight and wiper circuits on the B-CAN network in the event of a network wire or ECU failure that would effect the operation of the system.
Scheme 20
Messages are transmitted by an ECU (that monitors an input) over the communication circuit. ECUs that use the message (information related to that 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.
Scheme 21
"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
- Optional Security (LX model, SE model (Canada) option)
- Optional Unit (B-CAN option)
F-CAN ECUs
Scheme 22
- Gauge Control Module
- ECM/PCM
- Navigation Control Unit
- ABS/TCS (Traction Control System) ('03-05 models)
- VSA (Vehicle Stability Assist) ('06-07 models)
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.
B-CAN System Switch Device Index
| Combination Switch Control Unit | |
|---|---|
| Input signal | Output signal/device |
| Dimmer switch, Lighting switch, Passing switch, Turn signal switch, Wiper/washer switch, Intermittent dwell time controller. | None |
B-CAN SYSTEM SWITCH DEVICE INDEX - COMBINATION SWITCH CONTROL UNIT
| Relay Control Module | |
|---|---|
| Input signal | Output signal/Device |
| A/C pressure switch, Climate control switch, Daytime running lights control (Canada), Hood switch, Horn switch, Windshield wiper motor. | Daytime running lights control (Canada), Headlight, Parking light, Horn, Windshield washer motor, Windshield wiper motor. |
B-CAN SYSTEM SWITCH DEVICE INDEX - RELAY CONTROL MODULE
| Door Multiplex Control Unit | |
|---|---|
| Input signal | Output signal |
| Driver's door key cylinder switch (lock/unlock), Driver's door lock knob switch (lock/unlock), Driver's door lock switch. Driver's power window switches (up, down, auto up, auto down), Passenger's power window switches (up, down), Driver's power window motor pulser. | Driver's power window motor, Passenger's power window switches, Power window relay control. |
B-CAN SYSTEM SWITCH DEVICE INDEX - DOOR MULTIPLEX CONTROL UNIT
| Multiplex Integrated Control Unit | |
|---|---|
| Input signal | Output signal/Device |
| Audio-HVAC display module security ground, Brake pedal position switch. Door switches, Ignition key cylinder switch, Park pin switch (A/T), Passenger's door lock knob switches (unlock), Passenger's door lock switch, Power window motor, Seat belt switch (unbuckled), Transmission range switch (P, R position), Trunk latch switch. | Door lock actuators, Hazard warning lights, Interior lights, Ignition key light, Key interlock solenoid, Turn signal lights, Moonroof relay, Trunk lid opener solenoid. Door courtesy lights, Daytime running lights. |
B-CAN SYSTEM SWITCH DEVICE INDEX - MULTIPLEX INTEGRATED CONTROL UNIT
| Gauge Control Module | |
|---|---|
| Input signal | Output signal/Device |
| Dash lights brightness controller, Daytime running lights signal (Canada), Engine oil pressure switch signal, Washer fluid level switch signal (Canada), Parking brake switch, Brake fluid level switch, fuel level sensor, Select/Reset switch, Cruise control combination switch (set, cancel, resume, master). | Dash lights, Fuel gauge, Gauge lights, Indicator, LEDs, Speedometer, Tachometer, ECT gauge, Warning buzzer, Odometer/Outside temperature display. |
B-CAN SYSTEM SWITCH DEVICE INDEX - GAUGE CONTROL MODULE
| Climate Control Unit | |
|---|---|
| Input signal | Output signal/Device |
| Evaporator temperature sensor, In-car temperature sensor, Outside air temperature sensor, Sunlight sensor Air mix motor position (Driver's and Passenger's), Mode motor position, Blower motor control feedback. | Air mix control motors (Driver's/Passenger's), Blower motor transistor, Mode control motor, Rear defogger relay, A/C Request, Recirculation motor. |
B-CAN SYSTEM SWITCH DEVICE INDEX - CLIMATE CONTROL UNIT
