replaced battery in key fob...stopped working?

oldschoolvolvo · Post by **oldschoolvolvo** » 12 Apr 2013, 10:29

So I replaced the battery in my keyless entry key fob b/c it was only working close to the car, and after I put the new one in, the fob stopped working. I did some searching...do I really have to go to the dealer after I replace the battery? I called my local dealer and they said no reprogramming is needed after a battery replacement. I put the old battery in and it still doesn't work. Any thoughts? What am I missing?

Car: 1998 V70 T5

oldschoolvolvo · Post by **oldschoolvolvo** » 12 Apr 2013, 11:19

ok, so I solved my own problem. one of the small plastic tabs that holds the battery in place is missing so the battery would pop up after being installed an not contact the proper terminals. a piece of tape later and the key fob is back in action!

oldschoolvolvo · Post by **oldschoolvolvo** » 18 Apr 2013, 08:07

so perhaps I'm not out of the woods yet...the fob was working ok after taped down the battery but has slowly stopped responding to the "unlock" button. sometimes it will unlock the drivers door, but the typical double-click to unlock all doors does nothing. the "lock" button still works. i'm beginning to think the key fob is just wearing out...any thoughts?

Post by **abscate** » 18 Apr 2013, 08:17

Try another battery - sometimes you can get a bad one. You can also test voltage with a DVM and compare to new

Post by **erikv11** » 18 Apr 2013, 08:35

One thing that can totally revive a remote is cleaning it out with alcohol. But be careful do not use something like 70% rubbing alcohol as it has too much water and may damage the electronics. You can open up the remote and literally soak the electronics in some alcohol, work the buttons until crud breaks loose, then dry it out thoroughly after you clean it. Sticky buttons will go *click* again etc.

oldschoolvolvo · Post by **oldschoolvolvo** » 18 Apr 2013, 11:31

i got some electronics cleaner and thouroughly sprayed down the circuit board assembly of the remote, let it dry for a bit, put the battery back in and tried it. results are about the same...it's very intermittent. sometimes it consistently will lock, unlock all doors and other times it will lock but not unlock and other times do nothing...but if i put it down and pick it up a few minutes later and try it will work fine. if i reassemble it into its plastic case it will work for a little and then stop working. the symptoms seem to point to intermittent battery connection and/or maybe even a cracked solder joint on one of the switches. i measured the battery voltage at the B+ and B- locations on the pcb and am getting ~2.8v.

cambiecbc · Post by **cambiecbc** » 18 Apr 2013, 13:41

I got more or less the same problems like this before. The fob worked very intermittent for locking.
It worked after dipping a little WD40 to the micro switch with toothpick. It might be due the the decompressed mini spring and rust built in it. Just share my experience.

Post by **erikv11** » 18 Apr 2013, 14:56

I'm not sure that spraying electronics cleaner will do the job I was talking about - it is probably too volatile. The key part of my post up there is that you have to really work the buttons until the crud breaks loose in the switch, like what cambiecbc is talking about.

lefty45 · Post by **lefty45** » 05 Mar 2021, 11:01

FYI, this method worked with 91% alcohol on a 2018 Volvo s90. Soaked for 15 minutes and agitated by shaking. Also brushed with clean toothbrush and dried on low heat with hair dryer.
I know this is not the right forum but I was looking for a solution when I found this. Hope it helps someone else.

Post by **erikv11** » 05 Mar 2021, 11:25

Great to know that 91% worked thank you for posting. Sometimes it is hard to find 100%.