First, you will need Lock Grinder Schematic to be able to unlock these doors. To get the Lock Grinder Schematic complete the Buggy Parts mission.
Note. Without Lock Grinder, you can unlock these hidden doors and get access to the useful items that are inside them. So, your first priority should be to get Lock Grinder Schematic.
Lock Grinder Schematic
Electrical Wire Kit + Hardware Packet + Small Gears
Rage Grindable Locks Locations
Grindable Lock #1
Location. Look for a Grindable Lock near the entrance to Ghost Hideout. It has Ghost Pistol Card and Feltrite inside it.
Grindable Lock #2
Location. You will find the second Grindable Lock near the entrance to Wasted Garage. It houses CE Grenades.
Grindable Lock #3
Location. If you are out of supplies, go to B3 Floor of Wasted Garage and look for a Grindable Lock just past the electrified door. Open it to replenish your supplies.
Grindable Lock #4
Location. At B4 Floor of Wasted Garage, look for this door past the chaingunner on the car. Inside, you will find Supplies and Feltrite.
Grindable Lock #5
Location. In Shrouded Bunker, take the elevator to go down to the hallway. Search the hallway for a Grindable door. Inside which you will find Authority Machine Gun.
Grindable Lock #6
Location. There is another Grindable Lock at the entrance to Dead City Central. Inside it are Pinkies and Supplies.
Grindable Lock #7
Location. There is another Grindable Lock in Dead City Central. It can be found after the sandy area just before you climb stairs onto highway. Inside you will find large quantity of Feltrite.
Grindable Lock #8
Location. At The Wall, you should find a Grindable Lock when you encounter the third group of enemies. Look for it by the dead body. Replenish your ammo and supplies when you open it.
Grindable Lock #9
Location. After you have freed Marshall from the Authority Prison, follow him down the stairs and search for a Grindable Lock. Inside you will find Marshal Card and Feltrite.
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