WARNING!!! IF YOU DO THIS OFTEN ITS RISKY TO THE GAME / CONSOLE!

1: Go to scene player act 3 in the secrets menu.
2: Play the scene called "find my son"
3: When Jak goes around the car and find Damas under it open the disc and press triangle.
4: Put back the disc and wait for a couple of seconds and press continue.
5: You should now be in the place where the car crashed. You cant move.
6: Press restart mission and you will be able to move around!
7: Enjoy!