The Basics

Extracting the Base & Def files.

The first thing we need to do before we start making mods it extract the Base and Def files from the game folder. You will need the Game archive extractor that SCS software kindly made available on their website here.

Now you need to decide where you would like store your folder for the mods you are going to create. For the sake of this tutorial I will put it on my desktop. You can name this folder whatever you wish, I will call it ‘base2’. After creating this folder, extract the exe from the zip file you just downloaded from the ETS2 site and place the exe in the folder you just created.

Now we need to navigate to the game’s installation folder. Under windows 7 (disc) that will be:
C:\Program Files (x86)\Euro Truck Simulator 2 (on 64 bit) or C:\Program Files\Euro Truck Simulator 2 (on 32 bit).

Or C:\Program Files (x86)\Steam\SteamApps\common\Euro Truck Simulator 2 (on 64bit) or C:\Program Files\Steam\SteamApps\common\Euro Truck Simulator 2 (on 32bit) if using the Steam version.

The two files we need are the base.scs file and the def.scs file. So highlight these, right click and select COPY. Go back to your new folder ‘base2’ and paste the files into it. It is important that you copy these files, you must not cut or move them. They are required for the game to work and the originals must be left in the original folder.

We now have our copies of base.scs and def.scs in the ‘base2’ folder along with the extractor. First drag the copied def.scs file into the extractor. A black cmd box will pop up while it extracts the files. The def.scs file is rather small so it should be quick. The cmd box will disappear once it has completed. Once it has completed, drag the base.scs file into the extractor. Again the cmd box will pop up while it extracts. The base.scs file is very large (nearly 2gb) so depending on your system specs this could take a long time. It took just over 10 minutes for me, but it may be longer for you. Again you will know it is completed when the cmd box closes and you will be left with something that looks like this:
Once the extraction has fully completed, you may delete the copied base.scs & def.scs files.

Please note: When SCS release patches/updates/DLC, it is important to delete these files & folders and extract the content from the base/def files again after you’ve updated the game. There can be numerous amounts of small changes that could cause conflicts if you do not do so. Once you have extracted the updated files you should compare any changes SCS has made with the ones in your mods. A good example of this was the 1.3x update. They included new local currencies in the game. So if you had a modded an economy file from the 1.2x (or earlier) update and did not update it to the 1.3x update you would not be able to change currency from Euro to anything else. So it is very important to keep your mods up to date with the latest patch releases, particularly if you plan to release your mods to the public.

Opening the .sii files.

It is preferable that you download notepad++ this will be the easiest way to view and edit the .sii files.

Please Note: When the def files list prices, they are all shown in Euros. If you are using a different currency in the game, please remember to convert the list price to Euros. I will bring up the conversion aspects later.

Editing the def files.

Now we have everything ready, lets take a little time to look at some basic changes you can do with the def files. For this example I will take a look at the economy file. So go into the folder named ‘def‘ and find the ‘economy_data.sii’ and open it in your preferred program (I still highly recommend notepad++). Most of it is pretty straight forward.

The first editable line we come to is:

truck_refund: 0.35 # 35% of original price

Now I don’t think I really need to tell you what editing this will do, but for the sake of the tutorial, changing the figures will change how much you get back when you trade in/sell your truck. The default price is 35% return. Lets say we’re greedy and want to get 50% back. Simply change the figure to ‘0.50’ and the % number to 50%. You don’t actually have to edit anything after the # symbol as this is just a note, but I find it is best to do so for your own reference.

The next lines we come to are:

price_small_garage: 180000
price_garage_upgrade: 100000

garage_prod_plan_tiny: 20000
garage_prod_plan_small: 150000
garage_prod_plan_large: 300000

The first two as self explanatory. Price small garage is the price to buy a new garage and the garage upgrade is the upgrade cost to make it a large garage. The following three lines may not be so obvious to you. These are the expected incomes of running the garage over the course of a 7 day period. If you go into your “garage manager” in the game and select your garage you will see this:

As you can see I have a small garage. I am expected to make €150,000 or £120,000 in a week at this Amsterdam garage. Changing the prod_plan will change this amount. While it will have no baring on the game, it could be useful if you expect the garage to be making a specific amount that differs from the game’s default suggestion to your own expectations.

If we skip down a little bit we get to the AI stuff. Here you can edit how quickly they increase their skills, how much wage they get, fuel costs and things of that nature. One line I specifically want to bring up is this one:

driver_no_return_job_prob: 0.1 # 10% of no return job

This line as you can guess, relates to how often a driver can’t find a return job back to base. Some people find that 10% is too high and their drivers are constantly returning empty and costing too much. This would be the place to edit that. So if we wanted to half that and put it down to 5% you would edit the 0.1 to 0.05 and now there is less chance of them returning empty. Theoretically, you could make it 0% but I have not tried to do this, so do so with caution.

If we scroll to the bottom of the file, we can see the list of currencies.

currency_code[]: “GBP”
currency_ratio[]: 0.8
currency_sign1[]: “”
currency_sign2[]: “£”
currency_sign3[]: “”

So as we can see GBP is at 0.8 which is 0.2 lower than the default EURO standard. Hence why my garage productivity shows at 120,000 rather than 150,000. By changing this number you will change the ratio for the conversion. So if I was to make it 0.1 €150,000 would become £15,000 sound good right? No. You have to remember changing this will also change your income price. So if you were doing a job for €2,000 you’d now only be getting paid £200. This is purely a conversion ratio and nothing more.

Changing the Price

Just a math reminder. When converting a price for items in the game make sure you divide/multiply the correct way. For example: I use GBP so if I want to price my new Truck Skin at £2,000 I need to divide 2,000 by 0.8 which would make it €2,500.

Saving Your Edits

Do not simply press the save button! First we need to go back to the desktop and create a new folder to hold our modded files in. For the sake of simplicity, we shall call this folder ‘Mods’. The most important thing we need to know is that we have to keep the same folder structure that the original files we edited were in. So in case of the example above we need to create a ‘def’ folder (do not use capitals in the folder names or files names of the game folders) within the ‘Mods’ folder. Once we have done that you can use the “save as” to save the file in the folder we just created. Do not overwrite the original file we edited. In the future you may wish to edit the file again, so it is wise to keep the original file so you have some reference to the original values. The last thing you want to do is realise you need the original file and have to go through the extraction process again.

Once done you should have something that looks like this:

Now we need to prepare winrar to make the scs file to contain your mod. Back up one level so that you are in the ‘mods’ folder. Right click on the ‘def’ folder and select “add to archive…” – this will open up the wizard. First thing you must do is select the ‘store’ compression method and make sure the archive format is “zip”. Once that is done type in .scs in the ‘Archive Name’ box, then click ‘profiles’ and ‘save the current settings to a new profile’ and name it SCS. This will allow you to quickly select the .scs compression options with one click in the future.

Add the name you want to call the mod in the Archive name box. We’ll just use the name economy (though it is wise to name it something specific so you know exactly what it does). So you should now see this:

Press OK and let winrar do what it does. You should now have a file called economy.scs – move this file into your mods folder under ‘my documents’ – here: C:\Users\XXXXX\Documents\Euro Truck Simulator 2\mod (XXXXX is of course your computer profile name). Start the game, click “edit” on your profile, select your new mod and apply. Start the game and you should find your changes have been implemented into the game.
If you are using another program like 7zip, the important things to remember are that there must be no compression and it must be recognised as a standard zip archive format, not 7zip or rar, it cannot have a password and of course the file container must be .scs

You now know how to do basic modding of the .sii def files. Take a look at some of the other files in the def folder and see what’s in them. It’s the best way to figure out what is and isn’t editable for gameplay. One file you may want to look at is the police_data.sii file, this is were you will find information relating to the fines in the game.

On the next page we will cover the basics of modding trailers and company logos/name.

8 thoughts on “The Basics”

    1. It really depends on the truck. The basic set-up for the folder structure is


      But then it gets complicated. For some SCS trucks that is all you need. All internal data in the sii file will set up the engine. But for others like the Scania, there’s also a sound profile linked which add more lines and folders.

      So when it comes to a mod truck there could be numerous differences.

    1. You mean the tiny one truck starting garage? I’m not sure if that’s possible without modelling, I will take a look and see if it can be done with def editing though

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Dance demons, don't you know. This is a modding, modding tango.

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