CAN System…Your Car Has One!

I have written articles many times about the fact that your car is really a computer on wheels. They have up to 100 million lines of computer code and that is more than many jet fighters!  The most basic of vehicles have a minimum of 30 microprocessor-controlled devices.  We call these ECU’s (electronic control units). Luxury cars can have 100 ECU’s!

These processors make it difficult for the average person to work on their own vehicle but it makes it easier for auto repair shops as they have made an investment in the right equipment and diagnostic tools in order to translate trouble codes and determine what is actually wrong with your vehicle.

What do all these ECU’s do?  They help meet emissions and fuel-economy standards, do diagnostics, simplify design and manufacturing, reduce wiring, provide safety features, comfort and convenience. 

Controlling your vehicle’s engine is the most processor-intensive job and the engine control unit is the most powerful computer in your vehicle. It gathers data from dozens of various sensors and knows all that is going on.  It performs millions of calculations per second. The processor in your car runs more efficient code than that in your PC.

Each module communicates problems to a central module.  The problem is stored and then a technician can read the code using an off-board diagnostic tool.  There seems to be more and more technology going into our vehicles each year so more and more computer code will be necessary.  This is all part of keeping our environment cleaner and reducing the amount of accidents.  As we are moving toward the commercialization of the self-driving car we will find this will increase a great deal. 

The CAN (Controller Area Network) also known as CAN Bus enables all the electronic control units to communicate with each other…without a host computer.  This lets the vehicle’s electronic components; control units, microcontrollers, devices, sensors, actuators, and many more talk to each other on a single or dual-wire network. 

Your engine management electronic control unit is connected to the transmission electronic control unit, which is connected to the anti-lock braking electronic control unit, and so on!  There are essentially two wires involved; a CAN High and a CAN Low. Why is this important?  They act as a backup for each other in case one fails.  This is why your car can continue to run just fine with the check engine light illuminated. 

This is also why we tell you not to keep on driving miles and miles with the check engine light on…it really is telling you that your car needs attention.  You are already down to one wire…if the other one fails you have a problem!  Next time your check engine light illuminates, make an appointment and let our diagnostic technicians get your car back to excellent health.

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