Contributed by: theJrod






Had a lot of spare time last night, so I fiddled with the secret menu in the check control system.
Push
and hold the left dash button (system check). After about 10 seconds, a
menu will appear. Using the info from Ajay's post a few days ago, I


went on to see what all of them did.The following from 750i.de :
"Turn ignition to pos. II
Push

right button in the instrument cluster and keep it pushed. You will
first see "Check Control OK", some seconds later you will see "Test
Nr.01"
Push the left button on the instrument cluster to see the
car's identification number. Add the 5 digits together and write down
that number, you will need it for unlocking all the functions. Example:
DG23278 will lead to 2+3+2+7+8 = 22
Push the right button until you see "Test Nr.19"
Push left button until you see the number that is equal to the one you calculated above
Push right button again "
This will give you access to all the tests.
There

is a cool instrument test, along with actual vehicle speed (in Km/hr).
There is a digital tachometer with all four numbers (i.e. 2134 rpm), so
TommeyX could figure out his gear ratios down to the last digit. There
is current and average fuel consumption. Lots of other weird stuff that
I didn't want to mess with, but there does appear to be a reset
setting. The menu could be different for those with the on-board
computer option.
Also, an easy way to find out your speedometer

error. On the freeway, set the cruise control to the speed you want to
verify. Reset the average speed in your computer. The average will be
immediately re-calculated, and will basically give you the current
speed (assuming you are maintaining a steady speed). To reset the
average speed, press the button on the turn signal stalk so that ave.
speed is displayed. Now hold down that button for about 5 second. This
will reset only the ave. speed; you can also reset mileage using the
same process.
I found my speedometer to be off by about 4-5 MPH. Speedo said I was going 68, computer said 64.
Have fun and don't screw anything up.

theJrod