How to remove a 456 immobilizer box

There are two 10mm bolts holding 2 tabs just barely above the carpet and just below the edge of the seat bottom. Remove those 2 bolts and lift on the front of the seat bottom to remove. 

There is one 10mm nut that screws on a stud that holds the seat back in place. It is located at the bottom of the seat back up close. Once this nut is removed, pull the bottom out and slide it down to disengage the 2 wire tabs at the top of the seat back.

The trim piece below the window is held in place with one 10mm nut and two 10mm bolts at the back of the piece. In the front are 3 metal tabs that slide into metal brackets on the body. Once the nut and 2 screws are removed, the back of the trim piece can be pulled out a little and then slid forward, being careful of the rubber molding that covers the front of the trim piece.

Once the trim piece is off, the metal cover panel can be removed by removing the 9 TAMPER PROOF TORX screws. The torx bit can be purchased at any hardware store or at this link.  Harbor Freight security bit set

On the back side of the metal cover panel are two black boxes. The larger one is the immobilizer. The immobilizer is held in by three 10mm nuts.  Remove those nuts and remove the immobilizer box. There are 3 wiring harness plugs (note the center plug is just an antenna wire). Unplug these 3 and you have the immobilizer in your hands.

Reverse install making sure connections are seated firm, power up car at switch, wait 2-5 minutes for circuitry to stabilize. Proceed to normal start up of car.

Note that as the trim piece is slid back into place from the front, the trim piece being installed must fit behind the trim piece above the seat back; that takes a little pushing in 2 places: at the back to get it behind the existing trim above the seat and in the front pushing it against the body and back to engage the tabs into the brackets.)

TIP: Route the antenna wire out from under the metal cover to extend the range of the remotes, if desired.