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Car Electrical Parts Guide

Automotive electronics are electronic systems used in vehicles, including engine management, ignition, radio, carputers, telematics, in-car entertainment systems etc. Ignition, engine, and transmission electronics can also be found in trucks, motorcycles, off-road vehicles, and other internal combustion-powered machinery such as forklifts, tractors, and the excavators. Related elements for control of relevant electrical systems are found on hybrid vehicles as well as on electric cars.

Electronic systems have become an increasingly large component involved in the costing of an automobile, from only around 1% of its value in 1950 to around 30% in 2010.

The earliest electronics systems available as factory installations used to be vacuum tube car radios, starting in the early 1930s. The development of semiconductors after WWII greatly expanded the usage of electronics in the automobiles, with solid-state diodes making the automotive alternator the standard after about 1960, and the first transistorized ignition systems appearing in about 1955.

The availability of microprocessors after about 1974 designed another range of automotive applications economically feasible. During 1978, the Cadillac Seville introduced a “trip computer” based on a 6802 microprocessor. Electronically-controlled ignition and fuel injection systems helped automotive designers to achieve vehicles meeting requirements for fuel economy and lower emissions, while maintaining high levels of performance and convenience for drivers. Tsoday’s automobiles contain lot of processors, in functions such as engine management, transmission control, climate control, antilock braking, passive safety systems, navigation, and other functions.

Modern electric cars depend on power electronics for the main propulsion motor control, as well as for managing the battery system. In future, autonomous cars will depend on powerful computer systems, an array of sensors, networking, and satellite navigation, all of which will require electronics.


Automotive electronics or automotive embedded systems are distributed systems, and according to different zones in the automotive field, they can be classified into:

  1. Engine electronics
  2. Transmission electronics
  3. Chassis electronics
  4. Passive safety
  5. Driver assistance
  6. Passenger comfort
  7. Entertainment systems
  8. Electronic Integrated Cockpit systems

Engine electronics

One of the most demanding electronic parts of a vehicle is the engine control unit (ECU). Engine controls demand of one of the highest real time deadlines, as the engine itself is a very fast and complex part of a vehicle. Of all the electronics in any car the computing power of the engine control unit is highest, typically having a 32-bit processor.

A modern car may have up to 100 ECU’s and a commercial vehicle till 40. An engine ECU controls such functions like:

In a diesel engine:

  • Fuel injection rate
  • Emission control, Nox control
  • Regeneration of oxidation catalytic converter
  • Turbocharger control
  • Cooling system control
  • Throttle control

In a vehicle’s gasoline engine:

  • Lambda control
  • OBD (On-Board Diagnostics)
  • Cooling system control
  • Ignition system control
  • Lubrication system control (only a few have electronic control)
  • Fuel injection rate control
  • Throttle control

A lot more engine parameters are actively monitored and controlled in real-time. There are about 20 to 50 that measure pressure, temperature, flow, engine speed, oxygen level and NOx level and additionally other parameters at different points within the engine. All these sensor signals are sent to the ECU, which consists the logic circuits to handle the actual controlling. The ECU output is connected to different actuators for the throttle valve, EGR valve, rack (in VGTs), fuel injector (using a pulse-width modulated signal), dosing injector and many more. There are about 20 to 30 actuators in all.

Transmission electronics

These control the transmission system, mainly the shifting of the gears for a better shift comfort and to lower torque interrupt during shifting. Automatic transmissions use controls for their operation, and also many semi-automatic transmissions having a fully automatic clutch or even a semi-auto clutch (only declutching). The engine control unit and the transmission control exchange messages, sensor signals and the control signals for their own operation.

Chassis electronics

The chassis system has a number of sub-systems which monitor various parameters and are actively controlled:

  • ABS – Anti-lock Braking System
  • TCS – Traction Control System
  • EBD – Electronic Brake Distribution
  • ESP – Electronic Stability Program
  • PA – Parking Assistance

Passive safety

These systems are always ready to act when there is a collision about to take place or to prevent it when it senses a dangerous situation:

  • Air bags
  • Hill descent control
  • Emergency brake assist system

Driver assistance

Driver assistance consists of the following –

  • Lane assist system
  • Speed assist system
  • Blind spot detection
  • Park assist system
  • Adaptive cruise control system
  • Pre-collision Assist

Passenger comfort

Passenger comfort has –

  • Automatic climate control
  • Electronic seat adjustment with memory
  • Automatic wipers
  • Automatic headlamps – adjusts beam automatically
  • Automatic cooling – temperature adjustment

Entertainment systems

These have-

All of the above systems form an infotainment system. Developmental methods for these systems vary according to different manufacturer. Different tools are used for both hardware as well as software development.

Electronic Integrated Cockpit systems

These are new generation hybrid ECUs that combine the functions of multiple ECUs of Infotainment Head Unit, Advanced Driver Assistance Systems (ADAS), Instrument Cluster, Rear Camera/Parking Assist, Surround View Systems and many more. This saves on cost of electronics as well as mechanical/physical parts for instance like interconnects across ECUs etc. It’s also has more centralized control so data can be seamlessly exchanged between the systems.

Obviously, there are challenges too. Given the complexity of this hybrid system, a lot more rigor is required to validate the system for robustness, safety and security. For example, if the infotainment system’s application which could be running an open source Android OS is being breached, there could be a possibility of hackers to take control of the car remotely and may potentially misuse it for antisocial activities. Typically so, usage of a hardware as well as software enabled hypervisors are used to virtualize and create separate trust and safety zones that are immune to each other’s failures as well as the breaches. Lot of work is being done in this field and potentially will have such systems soon if not already.

Functional safety requirements

In order to minimize the risk of dangerous failures, safety related electronic systems need to be developed following the applicable product liability requirements. Disregard for, or inadequate application of these standards can give rise not only to personal injuries, but also severe legal and economic consequences such as product cancellations or even recalls.

The IEC 61508 standard, generally applicable for electrical/electronic/programmable safety-related products, which is only partially adequate for automotive-development requirements. Consequently, for the automotive industry, this standard is replaced by the existing ISO 26262, and released as Final Draft International Standard (FDIS). ISO/DIS 26262 describes the entire product life-cycle of safety related electrical/electronic systems for vehicles on road. It’s been published as an international standard in the final version in November 2011. The implementation of this new standard will result in developments and various innovations in the automobile electronics development process, as it covers the complete product life-cycle from the concept phase until it is decommissioned.


As more functions of the automobile are connected to short or even long range networks, cyber security of systems against unauthorized modification is needed. With critical systems such as engine controls, transmission, air bags, and braking connected to internal diagnostic networks, remote access could result in a malicious intruder altering the function of systems or even disabling them, possibly leading to injuries or fatalities. Every new interface gives a new “attack surface”. The same facility that allows the owner to unlock and start a car from a smart phone app also has risks due to remote access. Auto manufacturers may protect the memory of various control microprocessors to secure them from unauthorized changes as well as to ensure only manufacturer-authorized facilities can diagnose or repair the vehicle. Systems such as keyless entry rely on cryptographic techniques to make sure “replay” or “man-in-the-middle attacks” attacks cannot record sequences to allow later break-in to the automobile. 

In 2015 the German general automobile club commissioned an investigation for the vulnerabilities of one manufacturer’s electronics system, which could have led to exploits such as unauthorized remote unlocking of the vehicle.

Different Electric Components of a Car are –

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