Old Transponder/New Case/Key
 

Found lots of info on the web on how to program a new transponder chip, but nothing on this:

2003 Accord, plastic case housing key and transponder broke. Bought new case with blank blade, had blade cut, and installed old transponder in it.

Transponder still works. Key turns in ignition and starter grinds but will not start. Green key logo stays lit on dash. I tried the only other spare key I have - valet key with no transponder - just to make sure it wasn't a coincidence and car fires right up. Likewise if I put transponder back into old cracked case with old blade and use that it starts.

Somehow it "knows" it's a new key (darned if I know how). In fact, the only thing I was able to find online said no programming would be necessary.

FLASH - this just in. Found tiny immobilizer chip tucked away in old case (wondered what that little covered section in the new case was for), pried it out, put it in new key, bingo.

I'll leave this post up for any other dopes like me who might learn from it.

but the transponder is the imobiliser chip its the same thing ???

Nope. That's what I had thought. The transponder is a relatively large piece with the buttons on it, basically fills the entire plasti key housing, and which houses the battery. The immobilizer chip is a tiny (a little bigger than a grain of rice) black plastic piece that fits into a tiny section of the key housing. It's not programmable and if you held it next to the ignition switch and use a key that lacked one, the car would start. The hardest part of the whole operation (not that hard) was that the immobilizer chip is glued in place and has to be carefully pried out.

uhhh no http://en.m.wikipedia.org/wiki/Transponder_car_key and it definitely is programmable i had new keys made and re-programmed last year at a dealer even home depot can clone keys. but your rite about the transponder working via close proximity. i removed one from a spare key and made a new key with the handle of a screwdriver so it looks like i stole my car with a screwdriver in the ignition just like this http://technabob.com/blog/2013/05/07...-car-key-hack/

uhhh, yes. the transponder is programmable; the immobilizer chip is not. I was using the existing transponder in a new plastic outer case (with holes cut out to match the buttons on the transponder), so no re-programming was necessary. Not sure how I can explain it any better than I already have.

there is no immobiliser chip there is a transponder chip that is embedded in your key FOB thats what you replaced the key 'FOB'. the immobiliser is referring to the security system as a whole. did you not read the wikipedia page i posted ???. and once again the chip is definitely programmable how would you be able to use a newly made spare key if the chip could not be programmed ??

yes remind me next time to always get my facts from random people on youtube and completely discredit wikipedia.

I really don't know why I'm bothering to continue bickering with you, but ignorance compounded by arrogance always gets my goat.

You are arguing something I don't dispute but which is beside the point. I'll give it one last try in case it can help someone else; you are clearly beyond help since you already know everything.

Inside the plastic outercase is a transponder. It has buttons on it. It not only can be programmed, but must be programmed, as both you and wikipedia assert.

But there is also, in its own tiny little compartment, a tiny little plastic immobilizer chip. It is not a programmable chip, but simply one that must be in proximity to the ignition switch in order for the engine to fire. I'd take some pictures but, a) why bother, and b) if you watched to about the middle of the video I posted, you would see the two items in question.

Lastly, and most to the point: I put the old transponder and old immobilizer chip in the new plastic outer case with its newly cut blade. I did no programming. It worked.

I will now retire from what has been a really annoying discussion and let you have the last, doubtless incorrect and point-missing word.

Inside the plastic outercase is a ''transmitter''. It has buttons on it. But there is also, in its own tiny little compartment, a tiny little plastic ''transponder'' chip. It is a programmable chip otherwise you wouldn't be able to buy new keys. say i go buy a brand new key because i want a spare key what would you suggest to do in order to get it to start my car exactly. i have no idea what im talking about i was was just a mobile device tech for toyota and installed these devices for years.