How to take apart a Crossfire key fob,
without destroying it,
or making it look like your dog chewed it up:

First, it’s a good idea to know a few facts about the Crossfire key fob.

1. The fob is a transmitter, transponder, and physical key, all wrapped up in one.
2. The transmitter is used to lock/unlock the doors/trunk of the car remotely. It can also be used to set off the “panic” mode of the car.
3. A NEW fob’s transmitter can easily be programmed to work with your car.
4. A USED fob’s transmitter from another car can NOT be programmed to work with your car. (at least, I can’t get it to work)
5. When you put your key into the ignition, the fob’s transponder responds to your car’s ignition and replies with a special code, keeping your ignition’s kill switch from activating. (In other words, it allows you to start your car!)
6. Any fob’s transponder can NOT be reprogrammed to work with your car. (That is, not without VERY expensive equipment, rumored to be possessed by some dealerships. See PDF attached below.)
7. A transponder chip from YOUR car’s fob can be transplanted into another fob, and that fob will start your car, as long as you transplant your physical key along with it.
8. The physical key can be removed from a fob and placed in another fob. The physical key will always turn your car’s ignition and door locks, but without the correct transponder, your car will not start.
9. The ONLY fob that is guaranteed to work with your car is one that came with the car, and one that is ordered through your Chrysler dealer. New fobs cost about $130 – list price.
10. Another type of key is available, called a “flat key”. A flat key will physically unlock your car’s doors and will also start your car. But it is not a remote. They list price for about $60 from your Chrysler dealer.

What does all of that mean? The BIGGEST thing it means is that buying fobs off of eBay is a waste of money unless: your fob was damaged, and you’d like to put a spiffy new plastic case on your fob. That is what this thread is about: how to transfer your old fob’s guts to a new fob.

To transfer the guts of your fob to a new one, you have to be able to open up your fob without breaking the circuit board inside, and the transponder chip inside. Also it is important that you not damage the “new” fob’s case, or your work will be for naught.

The first thing you’ll want to do is grab a knife or a screwdriver and pry the case apart. DON’T! That’s not very effective, and also tears up the plastic of your case, defeating the purpose of replacing it.

The key to getting the case open without mangling it is a nifty little tool, called a snap ring plier. The interesting thing about these pliers is that they have narrow tips and when squeezed, the “jaws” open, rather than close. You can get a set of these pliers at any hardware store. As of 03/07/08, Harbor Freight has them on sale for $1.99. See this link:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=3316

 

Snap Ring Pliers:

 

Before you tear into your fob with your new snap ring pliers, you need to know what is holding the fob’s case together. Two things hold it together: some epoxy/sealant and two sets of “bumps” that snap into place when the fob case is sealed shut.

See the bumps circled below. Also, note the black marks around the edges of the “male” side of the case. That’s old dried up epoxy/sealant.

 

Now that you’ve seen what you’re up against, you know how to get this case apart.

Insert the snap ring pliers into the small gap that appears when you extend the key. Then gently squeeze, opening the front half of the fob. As you are prying open the front half of the fob, be careful not to allow the spring loaded key to pop out.

 

As you pry the two halves of the case apart, open it enough for the key release button to clear the bottom half of the case.

Then rotate the key assembly up and out.

Then pull the button and spring out.

Take care not to let the spring fly off by mistake. It's so small, you'll never find it again!

 

Now pop the red lens out. Just slide a fingernail under its edge and pry. It comes out easily.

Actually, you don't have to remove the lens. You can leave it where it is. Originally, I thought there was an LED that protruded into the lens from the circuit board, which you could break off if you didn't remove the lens before removing the circuit board. But it turns out that there is not an LED there, just a tiny transmitter, which doesn't protrude into the lens.

 

EDIT: I no longer recommend doing this step!

It is too easy to break components off the circuit board or to damage the circuit board. So don't use a lever/knife-blade on your fob. Just try to wiggle, bend, and pry the two halves apart. It is more important to break the epoxy holding the two halves together with a knife (see the next step after this one). You may even try heating the fob up with a hair dryer. I haven't tried this, but it would make the plastic a little more pliable and perhaps soften the epoxy.

Now the dangerous part!!

Slide something flat and hard between the two halves of the case. I used a pocket knife's blade. You could use a butter knife, putty knife, whatever.

Just be careful NOT to damage the circuit board. The knife will clear the components on the board as long as the board is still properly seated in the case. So push up on it before inserting the knife.

Slide the knife about half way between the two ends of the case. Then squeeze the two open ends of the case together. You're trying to pop the other end of the case open.

Don't squeeze TOO hard (like a vise or something) because you could break the circuit board. Just use your normal hand strength. If it doesn't pop, pull the knife out, and twist the bottom half (the half without the circuit board) back and forth.

Between the knife leverage, and twisting back and forth it will pop eventually. Just be patient and work at it. Don't force it, as you might harm the circuit board.

You can also run a very fine blade down between the two halves of the case. As you look down into the battery compartment, you'll see the seams between the two halves of the case. Running a blade down these cracks will help cut/loosen the sealant.

 

The cracks I mentioned above.


EDIT: I recommend inserting the knife blade into the cracks BEFORE you try to lever the case open. Without breaking the epoxy/sealant that is in these cracks, you'll have a VERY HARD TIME levering the case open.

ALSO: I have noticed recently that the original keys fobs I am seeing (from 2004-2008) are starting to become brittle with age. The original key fobs are coming apart a little easier, BUT almost every one I have done lately has cracked or broken in the process of getting it apart. So BEWARE: you probably won't be able to go back to your original key fob case if you attempt to open it up and swap the guts!

I have also see a new case crack and tear while opening it up. Most of the time it cracks or tears along the same lines as where I show putting the knife in to break the sealant/epoxy. After you reassemble the fob (and make sure it works) you can add a drop of crazy glue along the crack/tear to give it some added strength. But don't glue it until you know it works, as you won't get it apart again without destroying the fob's case.

 

Once you have popped the two halves of the case apart, you'll see the circuit board inside. It simply pops out. Inserting a finger into the battery compartment makes this very easy.

After the circuit board is removed, you MAY see a white plastic retainer holding the transponder in place. Sorry, I don't have a picture of the retainer. It just slides out, so no worries there.

Once the retainer is removed, you can see the transponder.

 

If you had a white retainer, then the transponder will just slide out. If you did not have a retainer, then your transponder is glued into place, and you must extract it.

Slide a thin blade under the transponder and GENTLY pry it up. I say gently not becasue the transponder is fragile - it is not fragile - I say it because the transponder is SOOO important. Without it, your car won't start!! So be careful not to damage it or lose it.

Note that the transponder is pushed a little bit forward into a small recess in the front of the case. So it will not pry all the way out. Just pry it enough to get a grip on it and pull it out the rest of the way.

 

You can also take the key assembly apart, removing the key shaft from its base. Use a small punch or a fine screw driver and tap the pin out through the other side with a hammer. Only light hammering is required. But it is easier to leave the key assembly together, and transfer the whole thing to your new case.

Now you have completely disassemled one key fob - your old scratched up or damaged fob. Take ALL of the parts and put them into a zip-lock baggie. This way you won't lose anything (like that tiny transponder chip) while you work on the other fob. Also, this will keep you from confusing which transponder is which.

It is also a good idea to mark the OLD (and working) transponder chip with a marker, so you can tell the difference between it, and the transponder from the fob you bought on eBay.

Now that you have some practice and experience, get your spiffy undamaged eBay fob, and disassemble it.

Take the key assembly, circuit board, and transponder chip from your OLD fob and put them in the NEW case.

To assemble the case, simply reverse the above proceedure.

Here's some assembly tips:
1) put a little dab of Elmer's glue on the transponder chip before you put it in the new fob. This will hold it in place while you reassemble the fob, and keep it from rattling around inside the case, if you don't have a white retainer.
2) When putting the circuit board back into the case, be sure that the metal flap (battery terminal) slides neatly into the slot in the case designed for it. If you miss, you could bend the terminal or even break it off the board. Then you'd be screwed!

 

3) Take care when putting the key retaining button and spring back together. They only go one way. Notice the two ends of the spring are different. One end has a peice sticking straight out from the spring - this end goes onto the gray shaft on the bottom of the case. The other end of the spring has a peice sticking into the center of the spring coil - this end goes into the black button. This end of the spring only fits one way into the button. Slide the spring in and turn it until you feel it click into place.

4) When you slide the spring over the grey shaft on the bottom of the case, note that the spring lines up with a slot at the bottom of the shaft.

 

5) After you have put the spring back in the button, and slid the spring over the grey shaft, put the kay assembly back over the black button. Be sure that the bumps on the button line up with the notches in the key assembly. The key should be pointing in almost the same direction as it would if you were about to insert it in the ignition.

6) Rotate the whole key assembly counter-clockwise one full turn, placing it under tension. Then place the bottom half of the case into the upper half of the case and snap them together.


7) After you have assembled your fob and tested it and you know it works, then you should pry open the new case a little bit - with your fingers or the snap ring pliers - and add a little crazy glue to help keep the case tightly together. Since we had to break the original epoxy keeping the case together to get it apart, it is prone to come apart more easily now. The glue will keep this from happening. BEWARE: once you glue it with crazy glue, you won't get it apart again without ruining the fob's case! So make sure it works before gluing it. Also be careful where you put the glue so it doesn't accidentally glue the battery lid or the key in place.

 

WOW! What a great write-up. Thank you! I’m one of owners ‘dumb’ enough to buy a fob off of ebay thinking all it needed was a new cut key and all would be good after reprogramming. However, I quickly learned about the complexities of the fob with its transponder and the laser cut key. At least you have confirmed that the $20 I spend on the ebay fob wasn’t a total waste of $$, and it might be somewhat useful down the road.

I do have one question for you. I would think that if the original key and transponder were transferred to the ebay fob, then the ebay circuit board could be programmed to open the doors, etc. I think you said or implied that is not possible? Have you actually tried that? Thanks again for the detailed info. I am sure I would destroy the thing without it. Now I might have a chance if I ever need to do a swap. I do have two working fobs. I just bought the one from ebay for backup without knowing what I was getting into!

 

your a genius!

 

First class guide, thank you (and good timing)

 

No problem fellas. I'm glad you liked it. To paraphrase the seatbelt folks: "If one fob was saved, it was all worth it."

Corfire:
As for reprogramming the circuit board (transmitter) from an eBay fob to work with your car, it SHOULD be possible, and I don't know why it isn't, but I haven't been able to make mine work. I've followed the fob programming directions to the letter and it never works. I'm hoping that someone else might know why, or what I'm doing wrong.

On the good side, now that you can take apart your fob safely, you can try it out yourself. Then, hopefully you won't have wasted your $20. Don't feel bad though, I wasted $60, and I have four useless fobs lying about. At least the case on my working one looks nice.

 

I got some information on the Crossfire key fobs from a locksmith database on cars. I copied what they had to say into PDF format. I've added this document to the first post in this thread.

The significant thing is that this "print out" seems to indicate that a dealer CAN reprogram the transponder in a key to work with your car. So, those ebay fobs might not be such a waste of money. We just need to find a dealer that knows how to do it, and is willing to do it without breaking the bank.

 

this is great ,,,,thanks,
being i lost one of my fobs, with this info i may take mine apart and superglue the the trabsponder to dash next to the key ,then i can use my spare key that with out the transponder doesn't work thanks again, jim

 

Hello to all that responded. Tom 2112, youre great. Will play with taking my fob apart. Will elt you know how it turns out.