Fixxxer

[EDIT: 2015/04/01] I've added a second 'fix' below this one. Check them both out and choose the one you'd like to try. My 2004 996 Targa key fob started acting up recently. It got to the point where I could press any of the three buttons and the LED would light up, but the car wouldn't respond. Sometimes when I would give the key a good whack on my palm it would work properly for a second, but then stop. Since the key's LED would light up with any button press, I knew that the buttons themselves were functioning properly. And because I could get it to sometimes work by hitting it, I was sure that there must be a broken solder joint somewhere on the PCB (Printed Circuit Board). Here's how I fixed it by using a heat gun to reflow the existing solder. Items needed: - Aluminum foil - Heat gun - Soldering iron - Solder Open up the key and pull out the PCB. Leave the battery in and try pressing the unlock button while putting pressure on different areas of the PCB to make it flex very slightly. When I did this, I found that applying pressure to one specific area would make the unlock button work every time. This just verifies that there's a bad solder joint somewhere. Remove the battery and desolder the plastic battery holder (two solder joints - easy to get to.) This is necessary because we'll be using a heat gun a couple of steps later and you don't want the battery holder to melt. Take a piece of aluminum foil and press it tightly against the side of the PCB with the key's buttons. You want to make sure that it conforms as much as possible to the shape of the PCB and all of its components. This servers two purposes: (1) it helps radiate heat away from the downward-facing side of the PCB, and (2) if any of the solder joints on the downward-facing side do melt, the aluminum foil will help hold the components in place. Set the key fob on a hard (nonflammable) surface with the foil/button side down. I used a metal baking sheet that I had in the garage. Cut a small piece of solder from your roll and place it on the top of the PCB. Make sure it's not near any of the electrical components. You don't want to accidentally create a short by having your solder melt to anything important! This piece of solder will be your control to let you know when everything has reached the correct temperature. NOTE: I ended up moving my control piece of solder from where it's shown in this photo (top left) to one of the holes where the battery holder was soldered on. This kept it from blowing around when I turned the heat gun on. Turn your heat gun on and move it back and forth over the exposed side of the PCB. You need to keep it moving to make sure that no one spot gets too hot. As soon as you see your control piece of solder start to melt, turn the heat gun off. This means that the existing solder has reached its melting point and should have reflowed to fix any broken joints. Let everything cool for a couple of minutes, re-solder your battery holder, insert your battery and give it a try! ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- If the above method doesn't work for you, try this: While the reflow method worked for me, it ended up only lasting for a couple of months before my key fob started acting up again. After taking it apart again and performing some diagnostics on the circuit, I discovered that the transmitter itself is what was causing the problem. Several of the solder joints weren't making great contact, likely caused by the PCB flexing in the key fob's housing over time. To fix it once and for all, I used a fine-tipped soldering iron to reheat the solder on each pin of the transmitter while I applied downward pressure to the top of the transmitter itself - ensuring a good connection. I'm going on about 4 months now after the fix and it's working like it's brand new! Open up your key fob, desolder the battery holder, and locate the transmitter (circled in the image below.) I soldered some AA batteries on mine for testing the circuit... Ignore those. :) Use something like a pencil eraser to apply pressure to the top of the transmitter. At the same time, very carefully touch your soldering iron to the top of each pin on the transmitter to re-melt the existing solder. Make sure that you only leave the soldering iron on each pin for, maybe 1 second - if that long. Too long could overheat and ruin the IC (Integrated Circuit.) After reheating a pin, make sure to lift the soldering iron straight up and wait a few seconds for the pin to cool before moving to the next one. Lifting the iron straight up, as opposed to sliding it from pin-to-pin will insure that you don't accidentally create a short between two pins with some solder stuck to your iron. I don't know if this last step helped or not, but I added a small roll of tape to the top of the transmitter. That way, after soldering the battery holder back on, it will keep a constant bit of pressure on the top of the transmitter - Hopefully keeping those solder joints from "cracking" loose again. Just re-solder your battery holder back on and you're all done! Good luck!