CAN DiagnosticsLeanna Beall

Western State College

CIS 235

CAN DiagnosticsWestern State College

Leanna BeallCIS 235

CAN - Controller Area Network- The wiring system in Automotive vehicles that are used

to connect all modules in the vehicle.- What allows different modules to share data between each other, and interact in ways that were not possible before.- All modules are able to speak to each other through the

wiring system.

Testing: - Mechanics have to have a specific scan tool that is

able to communicate with the PCM(Power Control Module).

- The PCM collects codes that are sent from other modules, and sends a DTC (Diagnostic Trouble Code) to the tool that is specific to a problem that has occurred.

Information Sent and Received:- Every module can send and receive information through the wires.- Every module has a specific address given through the network.- All information moving over the network is coded so other modules do not

recognize what module has sent it.- Sent as series of 0’s and 1’s.- Using a scope you can see the wave patterns where:

- Low voltages are 0’s.- High voltages are 1’s.- Operate on 5-7 voltages.

CAN Travel:

-Bus is the circuit that the modules use to carrie the information. May have one or two wires depending on the “class”- Class A- the slowest circuit. Carries 10

kilobits or less per second. (only used with simple command functions)

- Class B- carries 10kbps – 125 kbps. Dependent on the operating protocol. (more complex info.)

- Class C- Fastest class rating. Can operate up to 1 megabits per second. (100x faster the Class B)Most vehicles are running on Class C and are operating on about 500kbps.

Faults:- If one module is not working it can cause to much traffic on the

wires and PCM which can cause the whole vehicle to shut down.- If the PCM loses connection to other modules can cause all modules

to lock up, and cause many larger problems.- CAN networks are not manufactured in vehicles or starting to be

discontinued because of the many problems and the complication on fixing any networking problems. Produced by:

- Robert Bosh Corp. in 1894.- In 1992 the first production of CAN was manufactured in Mercedes-Benz

models.- By 2008 all passenger cars and compact trucks have the CAN network in

them.

Work Cited

-http://www.aa1car.com/library/can_systems.htm

-http://www.google.com/imgres?q=CAN+Diagnostics&hl=en&gbv=2&tbm=isch&tbnid=KsGarC-qSd3XGM:&imgrefurl=http://www.aa1car.com/library/can_systems.htm&docid=9r7sM8f3jBxQZM&imgurl=http://www.aa1car.com/library/auto_networks.gif&w=679&h=431&ei=QEXdTtbTGom22gW60tStDg&zoom=1&biw=1280&bih=758&iact=rc&dur=94&sig=115321413225900442551&page=1&tbnh=104&tbnw=164&start=0&ndsp=27&ved=1t:429,r:2,s:0&tx=107&ty=55

-http://www.google.com/imgres?q=Snap-On+Scan+Tool&hl=en&gbv=2&tbm=isch&tbnid=Q4XAmVjifYKnfM:&imgrefurl=http://ocw.weber.edu/automotive-technology/ausv-1320-automotive-electronics/17-serial-data/generic-scan-tools&docid=XDpLIWNvUaYk0M&imgurl=http://ocw.weber.edu/automotive-technology/ausv-1320-automotive-electronics/images/Snap-onMTS2500ScanToolSmall.jpg&w=480&h=247&ei=2UrdTrOQDoji2QXSwcHUDg&zoom=1&biw=1280&bih=758&iact=rc&dur=407&sig=115321413225900442551&page=1&tbnh=104&tbnw=203&start=0&ndsp=16&ved=1t:429,r:0,s:0&tx=83&ty=67

-http://www.google.com/imgres?q=CAN+Diagnostics&hl=en&gbv=2&tbm=isch&tbnid=6LzHoO5f82YzJM:&imgrefurl=http://www.talktomycar.co.uk/can.htm&docid=489C99X7A212rM&imgurl=http://www.talktomycar.co.uk/images/bywire2.jpg&w=599&h=432&ei=QEXdTtbTGom22gW60tStDg&zoom=1&biw=1280&bih=758&iact=rc&dur=204&sig=115321413225900442551&page=2&tbnh=149&tbnw=206&start=27&ndsp=15&ved=1t:429,r:7,s:27&tx=109&ty=101

What is CAN?

• Controller Area Network• CAN allows different

modules to share data between each other, and interact in ways that were not possible before.

• The modules are able to speak to each other through the wiring system.

Produced by:

Robert Bosh Corp. in 1984.

1992 first production in Mercedes vehicle

It was made to advance the onboard electronics in automotives.

CAN Diagnostics

Testing• Mechanics have to have a

scan tool that produces the codes that are indicated though the PCM.

• All modules send information to the PCM, which is used as a Host to store all data until received through the scan tool.

Sent and Received• Every module attached to the network can

send and receive signals.• All modules have there own unique

address through the network.• All information moving over the network

is coded so other modules do not recognize what module has sent it.

• Sent as series of 0’s and 1’s. Using a scope you can see the wave patterns where:• Low voltages are 0’s.• High voltages are 1’s.

Operate on 5-7 voltages.

CAN Travel

• Bus is the circuit that the modules use to Carrie the info.• May have one or two wires depending on the “class”

• Class A- the slowest circuit. Carries 10 kilobits or less per second. (only used with simple command functions)

• Class B- carries 10kbps – 125 kbps. Dependent on the operating protocol. (more complex info.)

• Class C- Fastest class rating. Can operate up to 1 megabits per second. (100x faster the Class B)• Most vehicles are running on Class C and are operating on about 500kbps.