Add a 3rd button to a 2-button wagon fob

Our 2001 Jetta wagon (TDI conversion) came with two 2-button key fobs. Our other car is a 99.5 Golf with 3-button fobs and I really like having a separate button for the hatch. The wagon doesn't even have a button inside the car to release the hatch and the 2-button fobs are really finicky about opening the hatch by hitting the unlock button twice quickly. Sometimes it works, sometimes not.

I decided to fix the problem by buying a used 3-button fob. The fob I received ended up being the wrong one. It turns out that the PO had replaced the part of the fob that contains the part number with a different one - probably because the chrome key chain piece had broken off. I did a little research and discovered that the correct part number for the 2001 wagon is 1J0959753T for a 3-button fob. (The 2-button fobs that came with the car are part number 1J0959753S)

So I bought another cheap used fob on eBay. When it arrived, I discovered that the seller had listed the wrong part number - it was 1J0959753P.

I was going to send it back but then I noticed that the circuit board on my 2-button "S" key had solder pads for a 3rd micro switch. Probably because VW used the same board for the "S" and "T" fobs. I decided to gut my two incorrect fobs and transfer two of the micro switches to my 2-button fobs' circuit boards. It was fairly easy to desolder the surface mount switches as they only have 4 pins. I then applied a generous amount of flux to the pins on the switches (flux really helps for surface mount parts) and soldered them to the empty pads on each of my "S" boards. I then put the "S" boards into the shells of my new fobs and tried them out. The hatch unlock buttons on each fob worked great so I didn't end up wasting any money on the used fobs - and now I have a pile of fob spare parts.

Here's a picture of one of my "S" boards prior to adding the extra switch:



Greg

Wow! That is a nifty Easter Egg type find! Neat!

It was useful for me, but I'm not really sure how many others it will help. There can't be a ton of people with 2001 wagons with 2-button fobs looking to upgrade. I wonder why VW stuck wagon owners with 2-button fobs and no hatch button inside the car...

However, what may be helpful to others is knowing that all the parts of the 3-square-button fobs seem to be interchangable, so if anything mechanical breaks or wears out on your fob, you can just buy the cheapest used one you can find, regardless of the actual part number, and mix-and-match the parts so that you get one functional fob.

Greg

This is the least old thread and the only one that mentions soldering, but I'm bumping this one out of the couple of choices. If the physical buttons start crapping out, you have a few options to choose from. I've measured the force to depress and have identified the parts: CK Switches KCS line.

The stock switch has a 3.5 mm high soft plunger, requires 3.5 Newtons of force, and has a rating of 300K actuations; PN KSC241GLFS: Mouser link, Digi-Key link
If you want a lighter actuation force, you can get a 2 N switch with the added advantage of a rated 1M actuations; PN KSC222GLFS: Mouser link, Digi-Key link

I meant to put these up here about 8+ months ago when ours needed refurbing.

Have you tried one of the softer switches?
I wonder if it actuates in your pocket in error.

It's about 60% the actuation force. I determined the actuation force of the stock switch my converting units and literally pressing it down on one of my scales; it was within the manufacturers tolerances. Your mileage may vary if you use a lower force switch.