In your PDA.
Hit Back to bring up your PDA. Type in: LB RB RB LB RB LB LB RB RB RB LB and hit the back button again. Then, hit back to access your PDA again, and without moving the cursor off the PMC enter one of the following.
Code - Effect
Up Up Up Down Down Down - Fill Fuel (Executable by either player, only affects the player who executed it)
Right Left Down Up Right Left Down Up - Give All Airstrikes (except nuke) (Executable by either player, only affects the player who executed it)
Left Right Right Left Up Up Left Up - Give All Supplies (Executable by either player, only affects the player who executed it)
Up Down Left Right Right Left - Give All Vehicles(25 each) (Executable by either player, only affects the player who executed it)
Up Up Down Down Left Right Left Right - Give Nuke (25)Up Up Down Down Left Right Left Right (Executable by either player, only affects the player who executed it)
Up Down Left Right Left Left - Infinite Ammo(Executable by either player, only affects the player who executed it)
Up Down Left Down Right Right - Invincibility activates for both players. If a client joins a game with an invincible host the client is made invincible as well)
Up Right Down Left Up - Unlock All Costumes(Executable by either player, only affects the player who executed it)
Up Left Down Right Up - Unlock Grapping Hook (When executed by either player, activates for both players. If a client joins a game, they have access as well)
You must have the Total Payback Update already to use these cheats.
To enter a cheat code, first activate your PDA while in the game, and next enter the "Cheat Mode On" code below. Once Cheat Mode is activated, exit the PDA and accept the on-screen message. Now return to the PDA and enter as many of the below codes as you'd like using the directional pad on the controller.
Cheat Mode On
L2, R2, R2, L2, R2, L2, L2, R2, R2, R2, L2
Invincibility
Up, Down, Left, Down, Right, Right *
Infinite Ammo
Up, Down, Left, Right, Left, Left **
Give All Vehicles
Up, Down, Left, Right, Right, Left **
Give All Supplies
Left, Right, Right, Left, Up, Up, Left, Up **
Give All Airstrikes (Except Nuke)
Right, Left, Down, Up, Right, Left, Down, Up **
Give Nuke
Up, Up, Down, Down, Left, Right, Left **
Fill Fuel
Up, Up, Up, Down, Down, Down, **
Unlock All Costumes
Up, Right, Down, Left, Up **
Unlock Grapping Hook
Up, Left, Down, Right, Up *
* When executed by either player during co-op, activates for both players. If a client joins a game where the host has unlocked it, both players will have access to it.
** Executable by either player during co-op, only affects the player who executed it.