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We provide a Mobile Car Electrics Diagnostic & Repair Service around Shropshire and Mid Wales areas. Tel 01743 884888
The aim of this page is to provide an insight into current modern vehicle technology and auto electrical engineering.

The development of Motor Vehicle Technology has responded to the consumer need for safe , comfortable and reliable transport that can meet the demands of environmental policies, economy and efficiency required in modern society through the use of advanced electronic systems with computerised control.
A top of the range luxury vehicle may have over eleven thousand electrical and electronic components forming a networked control and operation system.


A computerised vehicle control network consists of a series of electronic control units linked to each other . Data is transmitted digitally around the network on a "bus" system. Modules referred to as Nodes are connected together by a "physical layer". The physical layer can be a single cable , twisted pair or even an optical cable.
  Sensors  provide input data to the control units which process this information to command actuators which respond to the outputs of the control system.

The  vehicle CAN ( Controller Area Network) databus system may utilise a signal from one sensor for several functions, for example a speed sensor signal may be used for not only the speedometer reading but also linked to traction control, anti lock braking, engine management , speed related audio volume, rolling door locks and satellite navigation systems .
In the past this may have required individual sensors and wiring for each function but by using a network the number of wires and sensors can be reduced resulting in cost benefits for the manufacturer which may be passed onto the consumer. Multiple signals may be sent as a stream of information data on a bus wire.

A benefit of a vehicle data bus control system is that control units can "talk" to each other , for example when the brake pedal is depressed the brakes are applied, the brake lights switched on , and a signal sent to the engine management to reduce fuelling, and antilock braking function activated. This can reduce the quantity of cables inf vehicle wiring looms.

Network communication means that all data is available to all control units on the network. This multiplexed system can be used in diagnostics to identify faults.

Future vehicle network systems may be developed  to communicate with external systems by telematics , in a similar way to a model aircraft being controlled at distance by a handheld transmitter, or your computer being linked to a wireless network. A telematics system fitted to a vehicle with diagnostics would theoretically be capable of informing the manufacturer that the vehicle is about to breakdown before the inevitable occurred. Or if a traffic signal was on stop, it could transmit a signal to the vehicle to hold the brakes on until a go signal occurred.

The Nodes of a  network system may be linked together in Star, Line, or Ring formation.
The "Star" network has a central hub to which all nodes are connected, if this fails the whole network fails.

The "Line" network has spurs branched off a main communication line. If the main line is interrupted a secondary system is normally in place as backup so it can continue to function.

The "Ring " network links nodes in a ring (similar to the ring main electric supply in a house)

CAN uses a Line Network.

The nodes are normally linked by a twisted pair cable (ISO 11898) though a single wire standard (SAE J2411) has been developed.
The twin line system is favoured by the majority of manufacturers as it offers greater reliability , lower rate of failure, and faster data transmission speed. The two data lines are known as CAN-H (CAN High ) and CAN-L (CAN Low).

If a fault exists it can be diagnosed by connection of diagnostic equipment to a further line known as the "K-line " (ISO 9141)

Standardisation allows one manufacturer to link its system to work with that of another manufacturer , for example auxiliary body equipment fitted to a commercial vehicle enabled with a CANbus system could communicate with the vehicle engine.
Several CAN systems may exist in a modern vehicle. Different vehicle networks may run at different data transfer speeds, the individual networks may be linked at a specific node referred to as the "gateway". Seperation of networks can be employed by use of bus cut relays built in to control units to prevent one failed network interfering with another working network.
The structure of the CAN system and its data transmission has been defined by the International Standardisation Organisation (ISO) and the Society of Automotive Engineers (SAE)

Other Vehicle Network Systems

Other systems of networking data from control units in a vehicle exist including :
LINbus ( Local Interconnect Network) ;this is a secondary system to the CANbus.
MOST (Media Orientated Systems Transport) ;used for multimedia.
The "MOST" network uses optical transmission methods such as Photo diodes and fibre optic cable for high speed data transmission . This may be used for Audio,TV,and computer multimedia applications.

Byteflight (a BMW system)

D2B Optical (a Daimler Chrysler system)

Bluetooth ; used for wireless transmission of speech signals and data processing.

Power Line Communication ; This system integrates power supply and data lines.


The integration of electronic control to mechanical components is known as Mechatronics.

Mechatronics can be used for such repetative actions as control of the clutch enabling smooth gear changes and increased comfort.

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