Right, back to my poor wee broken Prius key fob. Something didn't feel right with the unlock button, in a tactile sense I mean. It was as if something had been knocked out of place within the inner mechanism of the button. I didn't know anything about the structure of the key fob. Google is my friend, however, and after a little digging about on the web I figured out a plan. Now it is worth mentioning that my remote key fob is not a smart (SKS) type - just the plain old standard key fob. I am sure the technique I used will be good for both. Without further ado, here is what I did.
- I got a scalpel knife, like the one shown below. Make sure the blade is as razor sharp as possible in order to get as clean and neat a cut as you can.
- Put the remote key fob on a hard flat surface with some protection in place. You don't want to damage a table if the knife blade slips.
- Make a cut with the knife as shown in the photo below. This is just to break the seal between the rubber membrane and the hard plastic case. Note: it was the unlock button on my key I was fixing.
- With just enough of the rubber membrane cut neatly along the seal between it and the hard plastic case, peel back the rubber membrane to expose the inner button mechanism. Each button has a hard white plastic microswitch - square in shape - fixed onto the circuit board. There is a circular 'plunger' at the centre of each microswitch. On my key, it was this that had been knocked out of alignment with its recess in the rubber membrane above. Gently tease the circular plunger back into alignment using your finger or tweezers. Test that the circular plunger by pushing it down. It should click. (You might even wish to test it by carefully taking it near to your Prius and checking if the door unlocks.)
- Now you are sure the unlock microswitch is working, carefully replace the rubber membrane. Ensure the recess within the rubber membrane covers the circular plunger of the microswitch correctly.
- Lastly, apply some Loctite / Superglue to the edge of the rubber membrane and the plastic casing and glue together. Keep fastened in place while the glue cures by applying masking tape or equivalent.
- Congratulations! Your key should be fixed and ready to use.
I now have a fully working remote key fob and it was fixed with standard household items. It has never come apart and always works when I use it. Incidentally, it was the same key that I used to take the photo above.