Key fob weirdness

Dropped my car off for some service earlier this week with the spare key. Battery turned out to be dead (I never use it); but no biggie they just started it with the dead fob maneuver.

So I went to replace the battery today - fob still inop. No LED light comes on. Checked the battery with a multimeter - works fine, 3.3 volts. Head scratching ensues.

Tried cleaning the contacts - alcohol + cotton swab did pull a little yellow something off - but they didn't look corroded. Now the LED sort of flickers on weakly but the car still doesn't register the fob's presence.

Perhaps there's more corrosion? Or is there some kind of reset procedure if the fob's been dead long enough?

Try another battery

Alan444 said:

Try another battery

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Yep, swap the battery with the one from the working fob is the best way to find out you have a bad battery. Sometimes the battery may be measured fine on voltage but not fine under load. Of course you may have a bad key fob but that's highly unlikely unless the key got dropped heavily or got run over. The remote key of our BMW 528i got run over by our CR-V accidentally once, although the key looked fine, but somehow the internal immobiliser chip got damaged and the key can no longer start the engine.

Works ok today! I did swap batteries with a known good, but then I swapped it back. Not sure if reseating the connections was the key or if somewhere in the process it reset the electronics.

craigo said:

Works ok today! I did swap batteries with a known good, but then I swapped it back. Not sure if reseating the connections was the key or if somewhere in the process it reset the electronics.

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As long as it's working, who cares ⋯