Common Vehicle Systems Operation Index

Learn how some common automotive systems work.


Learn all about many popular engines. Read articles for descriptions of engine mechanical, oiling systems, ignition, emissions, sensor locations, computers and more.


Stands for Anti-lock Brakes. If wheel slip is detected by the computer, the ABS system pulses the brake pressure to the wheels. Many parts make up this system. A computer, sensors, motors, wiring, valves.

Airbags - Supplemental Inflatable Restraint

Also know as SIR. Very important safety item used in conjunction with the seat belts system. Air bags are in more and more places in todays cars and trucks. Not only in the steering wheel and passenger front dash, but also in the side pillars next to the front seats, in the side of the seats, above your head- called curtain air bags, rear occupant side air bags.

Basic Electrical Theory

Most conventional vehicles use a 12 volt negative ground electrical system. The battery is the main component that is used to start the vehicle. The alternator is used to supply power to the cars electrical systems and to keep the battery charged. Testing electrical circuits is done with a Digital volt Ohm Meter (DVOM).

Diagnostic Computer Scan Tools

There are many types of scan tools. From the most basic models you can purchase at most auto parts stores, to the most high-end, cutting edge tools we use at the shop. These are invaluable tools to diagnose almost any system in todays vehicles. Depending on the capability of the scanner, you can read trouble computer trouble codes when the check engine light has come on with the most basic scanner, and manipulating and controlling most vehicle system for testing operation and diagnostic purposes on the most advanced and expensive types.

Engine Data Sensors

There are many sensors on todays vehicles to monitor all aspects of engine operations. From the fuel system, spark control, electronic throttle, engine timing, to emissions controls.

Exhaust Gas recirculation

Known as EGR. This is a very important component in the vehicle emissions system that has been around for decades in various forms.

Electronic Ignition

The electronic ignition system produces a high energy spark. This spark is used to ignite the compressed air/fuel mixture at the correct time. This provides optimal performance, fuel economy, and control of exhaust emissions. The cylinder that is at TDC of the compression stroke is called the event cylinder. The cylinder that is at TDC of the exhaust stroke is called the waste cylinder.

Fuel Injection

High pressure fuel is supplied by an electric pump in the fuel tank. Pressure is regulated by the fuel pressure regulator. The fuel injector is a solenoid operated device, controlled by the Powertrain Control Module (PCM), that meters pressurized fuel to a single engine cylinder.

The evaporative emission System (EVAP)

This control system limits the fuel vapors from escaping into the atmosphere. The EVAP transfers the fuel vapors from the sealed fuel tank to an activated carbon storage device, the EVAP canister. The EVAP canister stores the vapors until the engine is able to use the extra fuel vapor. When the engine is able to use the extra fuel vapor, the intake air flow purges the fuel vapor from the carbon element and then the normal combustion process consumes the fuel vapor.

Front and Rear Brake Operation

The hydraulic brake system consists of the following: Hydraulic Brake Master Cylinder Fluid Reservoir: Contains supply of brake fluid for the hydraulic brake system.

Power Steering

Power steering relies on a simple principle- a hydraulic pump running off a belt driven by the engine places a small amount of fluid under pressure, which in turn assists the steering mechanism in directing the tires as you turn the steering wheel. The system typically includes a pump, a pressure hose assembly, a control valve, and a return line.

PCV Valve (Positive Crankcase Ventilation)

A crankcase ventilation system is used to consume crankcase vapors in the combustion process instead of venting them to atmosphere. Fresh air from the throttle body is supplied to the crankcase.

Powertrain Control Module

The PCM is designed to maintain exhaust emission levels to Federal/California/other standards while providing excellent drivability and fuel efficiency. The PCM monitors numerous engine and vehicle functions.

Radio Shows LOC or INOP

Learn how the radio theft system works on your car or truck. Get the code to unlock your radio.

Secondary Air Injection System (A.I.R.)

The Secondary Air Injection (AIR) System reduces exhaust emissions following initial engine start up. The powertrain control module (PCM) activates the AIR system by supplying a ground to the AIR pump relay and AIR solenoid relay simultaneously. This action closes the internal contacts of the AIR pump relay.

Tire Pressure Monitor System

The tire pressure monitor system in todays cars use a radio frequency (RF) transmitter ( Tire Pressure Sensor ) in each wheel valve stem to relay pressure information to the module.

Stability or Stabililtrak System

The vehicle stability enhancement system (VSES) provides added stability during aggressive maneuvers. Yaw rate is the rate of rotation about the vehicle's vertical axis. The system is activated when the electronic brake control module (EBCM) determines that the desired yaw rate does not match the actual yaw rate as measured by the yaw rate sensor.

Displacement on Demand

Provides maximum fuel economy under light load driving conditions. The engine will operate on 8 cylinders, or V8 mode, during engine starting, engine idling, and medium to heavy throttle applications.

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