AutoECMs Blog — what is a body control module


What is an ECU - Electronic Control Module?

What is an ECU?

An Engine Control Module or Electronic Control Module (ECU) acts as the brain for your car. In fact some people call it the brain box.

ECUs are generally used to monitor and control engine functions such as determining what position the gas pedal is at while idling. This allows the car to know that when you step on the accelerator how much gas it needs to feed the engine based on the amount of throttle you’re giving it.

ECUs also control transmissions, telling the car when to switch gears while driving an automatic transmission vehicle. It can adjust the gear ratio depending on what setting it is put in - such as reverse, drive, overdrive, or sport. 

And some ECUs (known as Body Control Modules) control the function of the windows, door locks, and sunroof - basically all the accessories in or on your vehicle.

Before manufacturers switched to using engine control modules and a large network of computers to control the vehicles functions, everything was manual. Typically the only non-mechanical item in an older vehicle was the radio. Windows, door locks, and all the basic functions drivers now expect in their vehicles were manually operated. 

One of the primary functions of an ECU is monitoring a series of a cars actions to register errors with how it is operating. If an error is detected the ECU will generate a trouble code.

Once the ECU notices the problem and generates the trouble code, it will cause the check engine light to come on. When you notice that your check engine light is on, you should take your car in to have it examined by a mechanic.

The mechanic will hook your car up to an OBD scan tool like the Autel MaxiScan MS300 CAN Diagnostic Scan Tool for OBDII Vehicles and will register any OBD error codes that it may be sending. At this point the mechanic will inspect the location of the error and advise you of any ECU repairs necessary.

Unfortunately if your ECU is malfunctioning you may need to have the ECU repaired or replaced. If your ECU is damaged or the motherboard is corroded you will need a total replacement. Corroded or burned ECUs are generally not repairable.

ECU’s are integral to the operation of modern cars. These are not simple mechanical devices that you should attempt to repair on your own. Make sure that if you are experiencing any problems with your ECU you take it in to a mechanic as soon as possible.

The average cost for a brand new ECU from the original manufacturer runs around $1,500 per unit. Refurbished ECUs like the ones sells can cost a lot less and are a suitable replacement for your defective ECU.

AutoECMs has an extensive database of part numbers for most makes and models of cars/trucks/vans and more. The best way to confirm you are getting a suitable part is to pull the defective ECU from your vehicle to confirm the part number your specific automobile requires.

To learn more about ECUs, here are some good links that will explain the components of an engine's computer network.

Feel free to give us a call if you have any questions about your specific part or need to know availability and pricing. 1-800-900-0194