DIY Chevy Keychain Fob Repair

The fob to my wife’s Chevy Malibu began acting oddly – refusing to operate or only performing specific tasks, like opening the trunk but not remote-starting the car, etc. The fob battery was replaced but still no improvement.

She took it to the dealership and they said that there was a bad transistor inside so the whole fob would need to be replaced at a cost of $180. When she told me the story I asked her a couple of times just to make sure that I heard the word “transistor” correctly (and not, say, “transmitter”, which would imply the whole thing was shot). She said yes, that’s what the guy told her.

Since I have some experience in the area of electronics, the “transistor” comment sounded to me like the sort of thing made up to sound exactly technical enough to prevent any follow-up questions except for ones that sound like “Sigh. Do you take VISA?”

So, since the thing is “permanently and completely broken”, there was no harm in me popping it open (after giving my wife my little-used fob as a replacement, of course) to see what I could see.

Close inspection of the solder joints that hold the battery clip in place revealed tiny cracks, and the clip itself was a little loose. Cool. A couple of touch-ups to the battery clip solder joints is all it took. No expert knowledge of electronics or super-specialized equipment was necessary.

Here’s how I fixed my problem and saved $180 in about 5 minutes (Your problem might be different than mine, of course):

You will need the following:

• Small, flat-bladed screwdriver
• Electronic (not plumbing) soldering iron with a pointy (versus rounded or flat) tip
• Electronic (not plumbing) solder
• Flux (I always use flux when soldering instead of relying on flux-core solder. Some people don’t.)
• Cotton swabs
• Rubbing alcohol
• New fob battery (CR2032 for mine – yours might be different)
• Beer or wine

Do the following:

• Carefully pop open the fob using a small flat-bladed screwdriver
• Remove the circuit board from the fob
• Remove the battery from the circuit board
• Using a cotton swab and rubbing alcohol clean the inside of the fob (not the circuit board). Believe it or not, loose junk can work its way inside after a couple of years, and this junk might interfere with the operation of the unit.
• Do the same with the squiggly traces on the back of the circuit board (this is where the buttons contact the circuit board).
• Apply a very small bit (or drop) of flux to the three solder joints indicated in the picture.
• Using a very small amount of solder, gently touch up the three indicated solder joints. The battery clip will act as a heat sink so you don’t have to be too afraid of “burning up” the board during this step (within reason).
• Using the alcohol and swabs, clean any residual flux from the board
• Re-insert the battery
• Re-insert the circuit board into the fob
• Close the fob
• Test your unit (lock/unlock your doors, remote start the car, pop the trunk, etc.)
• If it worked, pour yourself a celebratory glass of beer or wine and enjoy. No, wait. Turn off the soldering iron first, and then have the beer or wine. Safety First, you know.

This has happened on both the fobs for the car, so I thought I would post this in case this is a common failure mode for these things. If this did not work out for you, I hope that something else will – good luck!