Key Fob Repair

You can split the two halves of the case with needle nose pliers inserted into the space where the mechanical key goes. Spread the pliers enough to insert a dull blade, and then work the dull blade the rest of the way around the glue joint.

The circuit board is jam fit into the case (no fasteners). Some glue may have overflowed onto the board. A small screwdriver works to dig the glue out of the way, and pry the board out.

There is a separate small chip (1/2" long by 1/8" square) without any connections on it. It's the transponder that is the active part when the keyfob is inserted into the slot in the dash.

If the rubber membrane is worn out, you may want to replace it by using another case from a used keyfob. Just look for the cheapest one you can find on eBay. Transfer your old circuit board and transponder to the replacement case.

Use a medium strength glue to put the case back together. You'll probably have to dig out some of the old glue. Don't use epoxy, contact cement, or other high strength glue or you'll never get the thing apart again.

While you've got everything apart, you may as well replace the battery.

 

Prising only works with the UK model. In NA you will need to pry it apart.

Tom

 

I've taken several apart, just to see what was inside. The circuit boards are different between the SKS and non-SKS systems. The cases are exactly the same, as is the transponder. The SKS case has a silver logo on it, but is otherwise exactly the same shape as the black logo non-SKS version.

One thing I wanted to do was to put the electronics into something smaller than the standard case. I haven't figured that out yet, but the transponder is useful by itself.

I keep a transponder key inside the car as an emergency backup. It is an ordinary transponder key intended for an older Camry, with the transponder replaced with one from a Prius keyfob. To start the car, I push the handle of the key into the keyslot - it works exactly the same as if the transponder were inside the keyfob.

So when I go cross country running or to the beach, I just carry a mechanical key to get into the car. Then use the transponder key inserted into the dash to start it. The $200 regular keyfob stays at home.

Question about the UK version of the keyfob. I understand that it only has the LOCK and UNLOCK buttons on it. The US versions have an additional button called Alarm. I suspect that the circuit board inside the UK version has the Alarm switch, but is missing the rubber button on top of it. Or maybe they just left the switch off the circuit board?

 

The alarm button actually sounds the horn on a US vehicle. Depending upon the option package, there is an alarm package that triggers the horn if the car is broken into. I'm not sure what exactly qualifies as a breakin, but one time I locked the car with the window open. When I reached through the window and used the unlock button on the door, the alarm went off. So I guess it would alarm if someone used a slimjim (professional coathanger...) to unlock the door. There is also an optional glass breakage sensor that can be installed.

We don't have any deadlock mechanism here. It must be a European thing, as our BMW does have it.

Another thing that seems to vary is the type of mechanical key. In the US, Gen1/Gen2 Prius have the ordinary edge cut mechanical key. For Gen3, the key is cut in a groove, while the edge is flat. They call it a laser cut key, but all the machines that I've seen are really milling machines with a mechanical bit. The extra security is simply that the cutting machines are still rare and expensive. And I suppose you couldn't cut a copy with a set of files. I've seen what looks like a Gen2 mechanical key on eBay that has the groove cut design, so there must be markets where Toyota uses that design with Gen2.

 

Interesting. My Prius has an extra horn for the alarm system, but it's just a horn. Could probably replace that horn with a siren. As for deadlocking, either you've got a different locking mechanism or the US version just doesn't activate the deadlock.

There is a glass breakage sensor that can be added as a dealer installed option. Other than that, there are no other sensors. The "reach through the window" trigger is just logic in the body ECU that says you have to disable the alarm before unlocking the door. The only ways to disable the alarm are with the keyfob or the mechanical key in the door lock.

I suppose you could add any number of sensors and connect them to the wiring for the glass breakage sensor.

LOL! Not very many. Most of the people who buy one are hardly into stealing. Preaching maybe, but not stealing.

Absolutely. But who would know how to use a transponder key in the keyslot? Since most of our Prius have the smart key system, many owners don't even know about putting the keyfob in the keyslot.

The main people that the locking systems keep out are the owners. Lose your keyfob and not even the roadside assist people can get your car going. They can get past the doorlock, but turning on the ignition requires a keyfob (or at least the transponder that's inside the keyfob).

There was a case in the news about an owner who lost their only keyfob. The car was parked 3 levels down in an underground parking facility. The dealer said to tow the car, but a tow truck was too tall to fit in the limited clearance available. This all escalated to asking the insurance company to total the car, as the car didn't work, and couldn't be fixed. After several days of local TV news coverage, a mechanic from a local dealership showed up with a scantool to reset the car security. But even that was a several round fiasco, as there wasn't any internet access in the garage, which meant that they couldn't get access to the Toyota website for an unlock code. I think what finally happened was somebody wrote down the magic numbers from the scan tool, walked to the surface and made a cell phone call back to the dealership. Another mechanic at the dealership used the magic numbers to look up an unlock code. Then a trip back down in the hole where the unlock code was finally entered into the scantool. You'd think it was a mine disaster for all the excitement...

No, I'm not worried about some crook breaking a window and figuring out how to use a transponder key in the keyslot. I'm a lot more worried about getting locked out myself.

 

Thanks for the report. Did you actually purchase just the membrane at your dealer?

 

Wow! 80 MB for under $12,000. First hard disk I owned was 10 MB for the bargain price of $300. Some company was unloading their last 10 MB disks (they had moved up to 20 MB and 5 of us scored on the old stock).

And congratulations on being Mr Fixit. Don't think I could fix a Prius keyfob using the junk bin at a Ford dealership. :rockon:

 

RobH, thank you for this post; the PANIC function on my 2007 Prius started going off at all hours of the day and night; by process of elimination, damaged membranes in the 9 year old key fobs (both of them) turned out to be the source of the problem, even when no-one was touching them. Following your advice, I bought new cases on eBay (C$24 for the pair), transferred the circuit boards and (after re-reading your instructions) the transponders, and snapped the new cases together (no glue seems to be necessary). Everything works just fine. Thank you!

 

UK based solution - I don't know if this helps, but the membrane on both my key fobs were worn through and the micro switches were going/gone. I found a place in London that will replace the micro switches and case. Pay online, post the key in and wait for them to return the repaired key (Google key fob repair). Turnaround was about five days, cost around £30 per key all in. Before anyone asks, I don't work for them, nor am I being paid to do this, I'm just so surprised that anyone still repairs anything these days that I had to share my find! This is the result: