Replacing Old FOB Case With New Empty FOB Case

I though I might post my experience with this because I've not found anything specifically on line in a cursory search. While it may seem dead simple I got tripped up and spent a day trying to figure out something that in the end was quite obvious....but, only if you know about it. I didn't.

My wife's 2006 I-tech (Australia) Prius original keys were in terrible condition. One had a split case and was held together with a rubber band, and the other had a destroyed "lock" key on the case. Fortunately the circuit board was fine if you could find the switch with a finger nail. There are numerous sources for empty FOB cases such as Ebay, Amazon, etc. They range in price from $9.00-$18.00.

Getting the electronics board out of the already split FOB was rather easy. It seems to be lightly glued in place and came away with little effort. It fit easily into the new FOB case. Opening the un-split case required quite a bit of work with a straight edged razor blade but was finally successful. After reassembly all seemed in order and the door opening/locking function worked fine. But, nothing would work trying to start the car! What I have not mentioned is that I also needed to replace the 12 volt battery at the same time as the case replacements. This certainly made the ensuing detective work more of a challenge because I incorrectly assumed that the FOB starting issues were more related to having had all power removed from the car.

Long story short (!) there is another part of the original FOB besides the electronics board that must be transferred to the new key. This is the "transponder" and it is black and blends right into the old case. It does have a serial number stamped onto it. It is located just above the battery holder and looks like an elongated triangle...much longer than tall. It is glued into a similar shaped bounded plastic slot. This must be pried away and placed in the new key FOB to allow engine start! Before I discovered this I had tried everything....disconnecting and recharging the 12 volt battery, Locking the car with a window open and taking the FOB far away and then unlocking from the inside, etc. Finally as a last ditch effort I put the old - now empty of electronics and battery - FOB into the dash and amazingly the car instantly started. That was the clue, of course, that I'd missed a vital step. This was a very close call because the FOB replacement had taken place several days earlier and I specifically told my wife not to throw any parts away. She did anyway and I had to fish the old FOBs from under a heap of garbage. All I can say is thank god there hadn't been a trash pickup!

 

The 2 cases I ordered came with no instructions at all. The RFID chip is certainly visible, but rather easy to ignore.