- Early automotive control systems in the 1980s-1990s had standalone modules with limited functions like lights and wipers and no communication abilities. - In the late 1990s and early 2000s, automakers introduced controller area networks (CAN buses) to link multiple electronic control modules and enable features like power windows and communication with scan tools. - Honda's 2003 B-CAN network was its body-controller area network that controlled multiple body modules and had full scan tool communication. It was also linked to the engine-focused F-CAN network. CAN networks reduced wiring complexity and weight compared to individual wiring harnesses.

1. B-Can System
ELS68-70

2. Early Systems
• 1986-90’s
• System had
stand alone
module
• Had limited
functions
– Lights
– Wipers
• No Scan tool
communication

3. Second Gen
• In 1996 the MICS
was introduced
• More functionality
– Windows
– Locks
– Moon roof
– Wipers
– Turn signals
• Limited scan tool
communication

4. B-CAN
• 2003 B-CAN
(Body-Controller
Area Network)
• B-CAN used to
control multiple
modules
• Full scan tool
communication
• Linked to F-CAN

5. Why CAN?
• Pre CAN cars used
multiple wires to
send information
• Wires = Weight
• CAN reduces
weight and
potential wiring
faults

6. How does it work?
• Multiple modules and
connected to the network
• Honda used Instrument
Cluster as “GATEWAY”
module
• Modules are connected by
two wires
– CAN HI
– CAN LO
• The modules use a High
Side Driver and Low Side
Driver to switch voltage off
and on
• The OFF and ON
represent the binary code
used to communicate
• There is a 120Ω
terminating resistor at the
end of the network to limit
noise in the system

7. Typical CAN Signal
• SOF (start-of-frame) bit – indicates the beginning of a message with a dominant (logic 0) bit.
• Arbitration ID – identifies the message and indicates the message's priority.
• Data Field – contains 0 to 8 bytes of data.
• CRC (cyclic redundancy check) – contains 15-bit cyclic redundancy check code and a recessive delimiter bit.
The CRC field is used for error detection.
• ACK (ACKnowledgement) slot – any CAN controller that correctly receives the message sends an ACK bit at
the end of the message. The transmitting node checks for the presence of the ACK bit on the bus and
reattempts transmission if no acknowledge is detected.

8. BCAN Diagnosis
• Verify symptom first
• Safety related system will be hard wired
– Wipers
– Head lamps
– Turn indicators
• Self test with HDS
• Mode 1 and 2 tests

9. Using HDS to “Split the Circuit”
• Use the HDS to
determine if fault
is a:
– Input
• DATA DISPLAY
– Output
• SPECIAL
FUNCTIONS
– Circuit

10. Using HDS
• Connect MVCI and pull DTC’s related to the
network.
• In you can’t pull codes…
• TEST MODE A
– Mode A will verify the units connected to the
network
– You must reboot HDS to see if there are any
changes.
• TEST MODE B
– Modules that don’t show connected can be
diagnosed here

11. Mode 1 & 2
• Mode 1 tests
communication
between
modules
• Mode 2 checks
inputs
– See service
manual for
correct inputs
• Results are
found in dash
display

12. Communication Problems
• If ALL modules
are down
– Suspect Short to
Ground in
network
• If only one is “Off
Line”
– Suspect open in
line to network

13. Other Networks
• F CAN
– Fast “real time” network used for VSA, ABS,
PGMFI, and AT
– K Line
• Diagnostic line used between modules and HDS
– S NET
• Remote starter network

14. End of B-CAN