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Toyota Land Cruiser Repair

Common toyota land cruiser problem in gulf. This is the most interesting case of Can Communication issue that would be answered and explained in person. Kindly, contact us to find out the reason of blinking warning signs on Toyota Land Cruiser. Watch the video below and enjoy.

What is CAN bus?

Your car is like a human body:

The Controller Area Network (CAN bus) is the nervous system, enabling communication.

In turn, ‘nodes’ or ‘electronic control units’ (ECUs) are like parts of the body, interconnected via the CAN bus. Information sensed by one part can be shared with another.

So what is an ECU?

In an automotive CAN bus system, ECUs can e.g. be the engine control unit, airbags, audio system etc. A modern car may have up to 70 ECUs – and each of them may have information that needs to be shared with other parts of the network.

Automotive Car with CAN Bus System
CAN bus wiring harness can-low can-high yellow green
CAN bus ECU network communication overview

This is where the CAN standard comes in handy:

The CAN bus system enables each ECU to communicate with all other ECUs – without complex dedicated wiring.

Specifically, an ECU can prepare and broadcast information (e.g. sensor data) via the CAN bus (consisting of two wires, CAN low and CAN high). The broadcasted data is accepted by all other ECUs on the CAN network – and each ECU can then check the data and decide whether to receive or ignore it.

CAN bus physical & data link layer (OSI)

In more technical terms, the controller area network is described by a data link layer and physical layer. In the case of high speed CAN, ISO 11898-1 describes the data link layer, while ISO 11898-2 describes the physical layer. The role of CAN is often presented in the 7 layer OSI model as per the illustration.

The CAN bus physical layer defines things like cable types, electrical signal levels, node requirements, cable impedance etc. For example, ISO 11898-2 dictates a number of things, including below:

  • Baud rate: CAN nodes must be connected via a two wire bus with baud rates up to 1 Mbit/s (Classical CAN) or 5 Mbit/s (CAN FD)
  • Cable length: Maximal CAN cable lengths should be between 500 meters (125 kbit/s) and 40 meters (1 Mbit/s)
  • Termination: The CAN bus must be properly terminated using a 120 Ohms CAN bus termination resistor at each end of the bus
CAN bus physical data link layer OSI model

Top 4 benefits of CAN bus

The CAN bus standard is used in practically all vehicles and many machines due to below key benefits:

CAN bus is low cost and simple

Simple & low cost

ECUs communicate via a single CAN system instead of via direct complex analogue signal lines – reducing errors, weight, wiring and costs

CAN bus is a fully centralized system network

Easy access

The CAN bus provides ‘one point-of-entry’ to communicate with all network ECUs – enabling central diagnostics, data logging and configuration

CAN is robust to EMI interference

Extremely robust

The system is robust towards electric disturbances and electromagnetic interference – ideal for safety critical applications (e.g. vehicles)

CAN bus is efficient with frame ID priority system for automated back-off interrupts

Efficient

CAN frames are prioritized by ID so that top priority data gets immediate bus access, without causing interruption of other frames or CAN errors

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