Skip the auto shop - Our mechanics make house calls
  1. Home
  2. Articles
  3. What Is a Vehicle's Electrical Control Unit?

What Is a Vehicle's Electrical Control Unit?

electrical control unit II

You’ll hear the term ECU bandied about in automotive circles, but what does it mean? The most basic definition is “electrical control unit” (ECU) which is a generic term applied to any system that controls a system or subsystem on the vehicle. This works in tandem with the TCU (transmission control unit) to control the entire vehicle. Many automakers combine the two into a PCM, or powertrain control module.

What does the ECU do?

Really, you can think of the engine control unit as one part of your car’s brain (it’s responsible for controlling the engine). Technically, the engine control module is an electrical control unit, but so is the TCU and a number of other controllers aboard your car.

Your ECU is responsible for monitoring all aspects of engine operation, making adjustments based on driver input, and more. It reads the amount of airflow entering the engine to adjust the throttle and it controls the Check Engine Light (at least partially). It also manages ignition timing, idle speed, variable valve timing, electronic valve control and more. Information is sent to the ECU from sensors located throughout the engine bay that do everything from measuring coolant temperature to camshaft position.

In short, the ECU has a huge impact on your vehicle’s operation, including everything from the available power to emissions control.

Some ECUs are upgradable through “flashing” them to change their firmware. This method is used to enhance performance beyond what the automaker intended. However, upgrading an ECU is not something that should be done outside of a specialty automotive shop.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

P0222 OBD-II Trouble Code: Throttle/Pedal Position Switch/Sensor B Circuit Low Input
P0222 code definition Throttle/Pedal Position Switch/Sensor B Circuit Low Input What the P0222...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...


Related questions

Q: I need new tires and also,my ceiling light works randomly

A great deal of the decision will be based on the type of driving you are doing. We don't endorse any specific tire manufacturers, so I will not be able to make a specific recommendation. We can help you with...

Q: hi i have a fiat sienna that has no pulse on the injectors from the ground in the ECU. the car has spark on the plugs and the pump

Hi there. No injector pulse, more than likely, is a faulty ECM. There are steps you can take to confirm the problem. Accessing the ECM (electronic control module) for codes may help direct you towards the area of fault. Having...

Q: Insert the key go to start everything. Goes blank releas back on battery is good starter also possible neutral safety switch or ig

Hello, thank you for writing in. Looking into and testing your ignition switch is the next step of your diagnostic process. If you have a voltmeter, you can test for voltage on particular terminals and see if the ignition switch...