BTW, when you say that you are not aware of different ways to start your game, I mean this :-
1/ If your wheel is correctly found by the game, when you run the game there is a START button that is used on the wheel, and you asked to press it during the game boot. If you don't know the button, try them all ...
By pressing this START button, you wheel is selected as your controller automatically.
2/ If when you are asked to press the start button, but you use the ENTER key on you keyboard, you have now selected the keyboard are your device to control the interface AND as your steering device.
3/ A common way of fixing wheel problems OR if you are one of those guys who edit the actionmap file for your wheel directly (like me), is to start the game with the keyboard ENTER key, and once you are in the game re-select your wheel. This forces the game to read that actionmap file again, either because you edited it, or because the game's stored settings have become corrupted.
As to the pedals:-
I suppose another way of checking your pedal settings, or perhaps fixing an incorrect setting, is going into the game and customising your pedal settings. After selecting your wheel, go into the settings, and see what axis has been assigned to your throttle and brake. If the settings show that they are both on the same axis, it COULD be the wrong setting for the pedals (incorrectly sensed).
Double check your settings by editing them. Select the throttle, hit your keyboard enter key, and then press your throttle pedal. This will assign and axis to your throttle. Is it the same as it was before?
Now do the same for your brake pedal, is that the same as before?
Probably more importantly do both the throttle and the brake get assigned the same axis? (usually positive and negative values on the same axis). Or does the throttle and brake show as being on a different axis? If so, you may just have fixed it.
Example picture of my G27 :-
The first one show the assignments when I use the normal throttle and brake pedals in the game. You can see that they are on different axis. (Y and RZ)
In this second picture I show MY current setting, because I don't use the normal brake pedal, I have assigned my clutch pedal as the brake (for left foot braking). Again they are clearly on different axis. (Y and Axisslider1)
If by re-assigning the throttle and brake pedals within the game fixes it for you, then great. If it doesn't, then this is where you probably need that profiling software (mentioned previously) for your wheel, so that you can change the red circled setting shown in the image in my previous post. (Combined pedals is de-selected)