CAN bus: not a public transport vehicle

You would be forgiven for thinking this blog is going to be discussing the pros and cons of your local bus service or timetable. I’m afraid this is simply not the case. Neither is it going to be anything as entertaining as the famous British sitcom, On the Buses. What it is going to focus on, however, is how a vehicle communicates internally. Still with me?

As a mechanical design engineer with more than a keen interest in old and classic vehicles, I am of course acquainted with a Controller Area Network (CAN) bus system. The CAN bus can be likened to a vehicle’s nervous system in that it allows for different parts of the vehicle to talk to each other. In a nutshell, it manages the communication of various sensors via a number of modules within the vehicle, through these interconnections to the electronic control unit (ECU) on the Controller Area Network.

'Invented' and developed by Intel & Bosch in the 1980s, this robust local network system eliminates the need for excessive wiring. Practically used in all vehicles, planes, trains and auto-mobiles, including tractors, ships, buses and many machines, a CAN bus system connects each part of a vehicle to the main dashboard; namely the operating point. It can almost be said to operate like a game of pass the parcel, when taking it in turns, every sensor passes a signal down the line, along to the next. In today’s modern world, when an average vehicle has well in excess of 100 modular parts of the ECU, this makes for further complications, as systems become more and more involved when additional 'gadgets' for the end user to play with, are added.

I’m currently working with a number of older vehicles in the Sanstec workshop that have CAN bus systems for all sorts of technical stuff, with this particular one on an older Range Rover, which following a couple of system issues, now has a CAN bus fault that I am trying to resolve. Wading through a 30 or so page document which explains how a CAN bus system works and referring to various technical details and manuals, I have thankfully cleared the issues with the ECU and cleared the error codes with diagnostic software and am currently replacing all the old sensors. It is certainly eye-opening as to how complex these things are and the problem is definitely exercising my technical engineering and problem solving capabilities. I am confident that my can-do attitude and engineering skills will eventually out-manoeuvre this temporary issue with the CAN bus system which should not be confused with a public transport vehicle.

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Source: https://resources.pcb.cadence.com/blog/2022-can-bus-history-at-a-glance