Are you sure you are using a breaker bar... or are you using a rachet?
You need a long breaker bar to break the nut loose. I would turn the ingnition key so that the wheel moves freely so that you do not break the locking mechanism of the steering wheel. Turn the wheel all the way to the left so that it can go no farther rather than take a chance on breaking the locking pin.
Then break the nut loose using the bar and realign the wheel to straight/square and pull it off.
[Edited by ejsharp on 05-30-2001 at 09:48 PM]
1993 190E 2.3
2000 Toyota 4x4 Tundra