What is an ECU Car SUV and Truck Computer Acronyms Explained

In this video, we're gonna be talking about ECUs and other types of modules in your vehicle. Whenever you're disconnecting one of the computers from the vehicle or the module, what you wanna do is disconnect the battery because you don't want a voltage spike in any of those modules that could cause internal damage. So what is an ECU? Well, an ECU is an engine control unit. Also, they can call this a PCM or an ECM. Some German companies even call it a DME. Now, you have to be careful with the term "ECU." Some companies call all of these modules ECUs, electronically controlled unit. This module is called a BCM or also a body control module. This is a FCM or fuel control module. And this module is actually a transfer case control module. But they're all called ECUs. Basically, they're computers or modules. So if you think of your engine like the heart of the vehicle, this would be the brain. And this is what's gonna control what's going on in your engine. It will get information from different sensors like the temperature, the airflow, and the position. It's gonna make adjustments so that you get better performance and better fuel mileage. Now let's talk about this module. This is the BCM or body control module. Some companies call this a CCM or a comfort control module. What this is gonna control is things on the inside of the vehicle such as the windows, the door locks. Even the horn or the alarm is gonna go through here.

Now let's talk about the fuel control module. Some vehicles won't have this, some vehicles, it's all gonna be used in the PCM, it's all gonna be monitored and dealt with in there. Some vehicles, it's separate. So this has its own brain telling the computer what to do. Here we have the TCCM, which is the transfer case control module. Now, this is gonna control functions of the four-wheel drive. Whether it goes in and out of four-wheel drive, it's gonna let everything know through this module. So these are just some of the modules in your vehicle. Now, you probably have 20 more modules in the vehicle and when they need to be replaced, they need to be programmed. They cannot just be plugged in and just drive away. Whenever you get a new one, definitely. And you generally cannot swap them from vehicle to vehicle. If you have an older vehicle, probably before 1996, you may be able to get away with inserting certain modules, swapping them. Most of the time you can't.

The reason why we have so many modules in a vehicle is so you can do more functions, so you can control more things like you can control a window with a module. You can control the lights with a module. And you can get more information. So if one of the sensors goes bad, it can tell this module that, "Hey, this isn't working so well." It'll send a code and then you can diagnose it a lot easier. So here we have a higher-end scan tool that we can actually look at the different modules and communicate with them. And when I say talk to a module, that's what I mean by "talk." You can communicate with it. You can see what's going on. There's 25 modules just on this screen that we can communicate with. Instrument Panel Cluster, Liftgate Module. So even in the liftgate, there's an actual module. Let's see what else. Passenger Presence System, that's something to do with the passenger airbag.

So when the passenger's not in the vehicle, the airbag on the passenger side would not deploy if it was in an accident. When it senses there's a passenger there, then it'll turn that airbag system on so the airbag will deploy in an accident. And then the radio. So, many modules. Remote Control Door Lock Receiver, that has to do with the remote itself. So there's a separate module for that. SIR Module is the...that's basically the airbag module. So there is a fault code in that module. So we can click on it and read that fault code. So, "Lost Communication with Passenger Presence Module." So that could have been something as low voltage, either low voltage from the battery or even a loose connection or something like that could have caused that. So this just shows that the modules are actually talking to each other, you know, this passenger presence module was talking to the airbag module, telling it...it wasn't seeing it so it came up with a code. And that gives us the direction, makes it a lot easier to diagnose.

So I hope this video helped you understand modules and ECUs a little better. If you enjoyed this video, make sure you subscribe to our channel. Ring that bell, turn on all notifications so you don't miss any of our videos.