Another key fob rebuild post?

[BlackBart]

I thought I'd post a DIY on my experience rebuilding g my broken key fob ('04 XC).

I made fun of this guy who fumble-fingered his way through, kept dropping expensive bits, hacked away at the case...


Now I understand. It's not as easy as popping it open and swapping parts.

Both our keys came from the previous owner with the blades locked in the open position. They have been opened and obviously tampered with. One of them would randomly act up and set off the alarm. I read a few posts here and bought a pair of ebay empty cases for $20-something from a high rated seller. Dirt cheap, worth the experiment. I got the ones with a keychain loop since the tiny holes in ours were broken or pried open.

The old one. The buttons were crooked, the emergency button had slipped into the hole. The tiny torx screw was cranked in there - I used some HD hardware for such a tiny screw.

New one open -

Then the trouble starts. I found that the entire upper section with the blade was filled with hard black epoxy. The PO's mechanic had filled all the voids and glued the halves together. First goal was the get the old blade out of there. It is hard plastic. There's a little glass transponder capsule somewhere in the upper piece - It's like an archeological dig in that you want to chop through the rock, but you have to make tiny progress with little tools in order to not destroy the priceless dinosaur bone in there.

OK, blade out. To this point I've used big snippers, tiny snippers, tiny screwdrivers as chisels, tiny needle nose pliers, and even a Dremel to very carefully split the halves. Two hours of slow and careful.

Ah HA! The dreaded chip / capsule / transponder!

[BlackBart]

It's embedded in the plastic and epoxy. I snipped and carved with a sharp utility knife, but I did not pry.

Then it's almost free, one more little snip....... ARGH, I've cracked the glass. ...

My mess is way worse than that German guys!

I got that little parallel ridge low enough, shaving with a utility knife, to loosen up the capsule.

And there it is...what a mess I've made.

There appears to be a tiny copper coil inside. I read posts here at MVS that it isn't ruined..... yet. And someone said don't use glue, not sure why. So I gathered the little dome end pieces and set the whole thing on upside down scotch tape with a tweezers. After a lot of fiddling I managed to roll up the tape around it like a tiny burrito. No pressure, not too thick.

I pinched the ends shut and trimmed them.

This is what was left of the upper section.....

[- Pete -]

Oh no, did you try starting the car yet with that cracked transponder?
I cracked mine too the other day. Actually I just chipped the glass & it immediately quit working. Yagger is making new keys for me. Dealership wants $270 for just a new switchblade key. That does not include any key cutting, software, IMMO programming (transponder marrying) OR labor costs!

If your transponder doesn’t communicate with the ring behind the steering column (like mine ceased to) any longer he can help you out for a lot less than the dealer.

[scot850]

I bought new transponder chips and a new key fob. Repaired my 2 non-functioning fobs (neither transponder worked and one had a bad spring on the flip key). Also bought 2 aftermarket cases.

Rebuilt both originals and had Volvo program the new one and the 2 old ones with the new transponder chips. Now have 3 working keys. I don't recall the key fob being that expensive from the dealer about 4 years ago? Maybe $140 CDN? I only needed the one part with the transponder in to get the program key. If you buy the whole unit it is $280 Cdn.

Neil.

[- Pete -]

Yes, full key price; that was the key (shell), keyless entry PCB, transponder and switchblade nose section of the key - $272 USD (1/21/22). I didn’t ask what the price was with my discount, didn’t matter as I was definitely not paying anywhere near $200 or more for a new, non-programmed switchblade key.

[BlackBart]

Sorry I didn't finish this, we were off to dinner.

Old key blade in new case. (Forgot to put the capsule in here and it had to come apart again - at least this one is easy to take apart) You learn to fiddle a bit with fitting and twisting the spring to load the flip key, then snap the lid on over the button.

Old guts to transfer. The original rubber tray is shaped much better than the new one, so the circuit board fits. I used it.

So...the punch line......

Went to the garage, and to my surprise it locks, unlocks, turns on the courtesy lights, unlocks the hatch...all good.
We were quite pleased with ourselves.

After Pete's post, I had to go back out and try it again..... Locks and unlocks just fine.
Then I tried to start it and it acted like a low battery - not dead, but clacking, no start. UH oh....

Got the other key, the one we always use, and it started the car after a couple of stumbles - wonder if that's from messing with the alarm and all that unlocking.

So I was hoping to provide a nice little write-up, but I wonder if I've done the opposite lesson, in how to not break the glass and screw up your keys.

[- Pete -]

Your photos are wonderful, and thank you for posting this. I believe that there are a lot of owners with the same issues & frustrations with the associated cost to rectify the loss of a key or it’s functions. The biggest issue in your case was that someone had already experimented with your keys. Were the keys unmolested, I think you’d have been fine.

In my situation, for my 2004 XC I have 1 switchblade key (of which I broke the transponder) and 1 (spare) valet key which also has a transponder. This leaves me with 1 option of starting the car (without spoofing the immobilizer) - the valet key. Sure my keyless entry function on my switchblade key still works, but it’s unwise to carry around the only 2 keys I have for the car just so I can remotely unlock/lock and start the car. I don’t like using the metal key blade in winter to unlock the drivers door and I’m unwilling to glue/tape my working transponder/valet key by the immobilizer ring just so I can use any plain cut key to start the car.

I personally would rather pay a fellow member/enthusiast who has developed his own software & can remotely achieve the same result as the dealership (and for far less coin).

Thanks again for posting this - so very timely.

[BlackBart]

I have some questions now, assuming I broke / ruined the transponder capsule.


1. What exactly does this thing do? It has no power source of it's own in there? It just bounces a signal back to the sender under the steering column?

2. Are there two systems involved with the key fob? One is sending a signal (with a battery) to the door lock system? Where is that receiver?

3. Then another system (using the device under the steering column) is allowing the computer to send spark or power to the starting circuit? So they can't steal the car, but they can get in and take anything.

4. What's inside this thing? I see a tiny copper electric coil. Is it in a vacuum? Does breaking the glass ruin it, or is an electrical contact shorting somewhere since it's not held in place anymore? How does that makes sense if there's no power source?

Here, orangex says it just has to stay dry, so tape it. Don't use glue he says -
viewtopic.php?t=92139

5. Why not just embed it in a tougher plastic shell? The thick plastic in the fob case has more electrical or signal insulation than the glass shell. Is the little bit of scotch tape shielding it?


<EDIT> Found this MVS post from 2015.... tru?
"When I tried to start my car, it didn't work and I had a "start prevented" message. Don't panic if you get that! All there is to do is to reset the immobilizer. To do this, simply lock and unlock a total of 5 times."

[BlackBart]

So right now we have the one good key that runs the car. Blade is locked open. No strap, easy to drop or lose in the bottom of someones purse.
Then this second one, with non-functioning transponder, but it will unlock the car.

And another new empty case.

Fine unless you misplace the one good key.

[BlackBart]

Here's a Chinese VW chip on ebay for 6 bucks. Looks very similar to ours. I see the coil and then some copper arms up the sides of the glass. Maybe one or both of these is touching the coil now.

s-l1600-1.jpg (36.98 KiB) Viewed 1302 times

s-l1600-2.jpg (30.47 KiB) Viewed 1302 times