Over time, my supply of keys for each of my cars inevitably dwindles. For our S430, one of our Smart Key's buttons cracked, and its operation became intermittent, even with new batteries. The emergency key's plastic hole is broken off, so it wouldn't stay on my key ring (I hated the thing anyway, since unlocking the door with the metal key always set off the alarm). So I'm down to one good Smart Key. I will probably order another key from the dealer ($198), but I decided to salvage the important parts of my damaged Smart Key, which should still work.

My choices were to get an old Smart Key from somebody, or a new Smart Key case, and then transfer the innards of my old key to a new one. I found a new case on ebay, and bought it for less than $40.

The new case is just the outer plastic shell, with no metal blade, spring loaded release mechanism, battery holder or circuit board. After removing the routine parts as described in the owner's manual for battery replacement, I could look inside the old case and see the edge of the circuit board, with a plastic piece on top of it. This spacer piece is held in place by two posts that fit into holes in the board. The challenge was to pull those parts out.

I decided to insert a pick into the rectangular hole in the plastic piece and pry the thing out. I held the pick parallel to the edge of the circuit board to do this. I partially succeeded , but broke off a piece of the plastic in the process. The plastic part was partially out, leaving room for me to carefully use needle nose pliers to pull the board out. Next time I may try to hold the pick perpendicularly, or maybe I'll just put a cutting wheel on my Dremel and take the case apart.

I then simply put the plastic piece back on the circuit board, and slid it into its new home. It is possible to put it in crooked, so it took a couple tries. I then put the battery holder and blade back in, and it seems to work perfectly.

I'm guessing that the case I got may not have been made by the same company that supplies them to MB, as the word "PANIC" isn't printed straight, but I'm optimistic that this thing will last a long time. Getting an old one (in good shape, at the right price of course) may have been a better way to go because then I would have gotten to practice removing the guts of the donor key before working on my original key, and maybe had an extra plastic spacer piece as well.

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1996 C280 289K Traded
1997 E420 167K Traded
2001 S430 240K Traded
2010 E550 4matic 80K
2000 GMC Jimmy 198K Gone to Boneyard
2003 Camry LE 196K
2011 Mazda3 i Sport 31K