Wrench Tip: How To Fix a Faulty Key Fob

Wrench Tip: How To Fix a Faulty Key Fob

by David Zipf

If you drive an older car with keyless entry, you will notice over time that the buttons stop working.  The general solution is to simply replace the battery.  But sometimes that doesn’t actually fix anything.  Other times only one button isn't working while the rest are.  If this is the case, the real problem lies deeper and fortunately, it’s an easy fix with some simple tools and about 5 minutes of time.


Once again, our new-to-us Mazdaspeed3 is both the source of this Wrench Tip as well as the guinea pig.  Our car is equipped with an aftermarket security system which has both a long range antenna and remote start (which I always thought was a dumb gimmick until I tried it.  It’s actually pretty cool).  Anyway, the lock button on our remote was giving us a lot of grief.  We would have to press it really hard to get it to work.  The unlock and remote start buttons worked perfectly fine.  Even after replacing the batteries, locking our car was a bit problem.
First things first, we disassembled our remote.  Three screws hold it together.  The battery stays in the (beat up) back cover.  Next, peel out the PCB and rubber membrane button cover.  Obviously your exact steps to get to this point will vary based on your own vehicle’s remote, but the goal is to free the PCB.  Pay no mind to the washer in the top left: it’s actually from my wah pedal which was also on the fritz and was in pieces while we were working on this remote.  
Well here’s our problem!  All of those rubber deposits are preventing the membrane switch from making good contact with the contact pads of the button.  The upper left contact set is our lock button, which seems to see the most use.  If we can clean off the mess, our remote should work perfectly.
Actual cleaning is surprisingly easy.  All you need is a bottle of rubbing alcohol and a few cotton swabs.  Simply use the alcohol as a solvent and rub it on the contact with your swab.  The alcohol will neatly dissolve any corrosion or rubber without damaging anything electrical.  Plus it dries quickly and cleanly.  If you have real electrical contact cleaner, feel free to use it instead.  Brake cleaner also works in a pinch, but be very careful as some automotive cleaners are far harsher than others.  
Much better!  If this doesn’t solve our dodgy button then our remote is in deep trouble.  While the remote was apart we also cleaned the inside of the buttons themselves which were also covered in gunk.
It took three passes to completely clean our contacts.  Gross!  While you have the remote apart it would be wise to replace the battery (if you haven’t already).  Then simply snap and screw everything back together and you’re all done!  For our Mazda this fixed the remote perfectly.  No longer do we have to smash the lock button like a gorilla just to get our security system to engage.  This procedure was so successful, we ended up cleaning the spare key’s remote as well, plus the remote for our VehiCross.  

As a final tip, if you’re an old school gamer like me who loves his old Sega Genesis, rubbing alcohol and swabs are the perfect tools for cleaning corroded old cartridges that don’t play right.  Simply swab the contacts of the cartridge with alcohol and watch how black the swab comes out.  It’s amazing how well this refreshes old games.  I’ve had flea market sourced games go from being unplayable to working perfectly with just a few seconds of work.  This also works well on funky game controllers (most video game controller buttons use the exact same switches as car remotes).  And this ALSO works on funky guitar effects, especially inside the female plug cavities (some power switches on your effects can also be cleaned with alcohol and swabs).  And since we have hit my personal trifecta (cars, games, and guitars), we can safely wrap up this Wrench Tip.  

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