Remote fob not working after battery change

[ChoonDoode]

Morning all,

 

Searching around on previous threads hasn't enlightened me as to what the fault may be....

 

Long story short, I got in the car the other Thursday and a message popped up on the dash saying change key battery. Not a worry as I've already done it before because the key which I'm using is the 2nd key because I changed the battery on the 1st key about a year ago. I was using the 2nd key because I didn't want to get stuck somewhere if the key stopped working. Even though the 1st key was back working, I'd just carried on using the 2nd key.

 

I had ordered a few 2025 batteries this time just so I've one or two pair and with the bank holiday, they've not long come.

 

New battery prepped, cover off, old battery out, new one in and cover back on. SORTED. Or maybe not..........

 

The light isn't lighting up on the fob (it was previously) and it's not doing anything to the central locking. I've checked this new battery in the working fob and all is fine, so it's not the battery. The handbook says about having to sync the battery by pressing a button on the fob and unlocking the car with the door lock, but I'd be expecting the fob to still have a light on when I press a button sync'd or not.

 

Can someone think of what's gone wrong in this instance?

 

thanks

[FrankNicklin]

I had this issue only last week. Replaced the battery and the fob would not work. I took the new battery out a few times, even replaced the old battery and it would not work.

 

I then cleaned the contacts inside, and reseated the battery making sure it is fully seated and not at an angle. Been working fine ever since.

 

This is the second time I have replaced the battery in the same fob and the first time went off without a hitch, but the second time was a bit troublesome.

 

If the red light on the fob isn't flashing, its not a sync issue, but the fob battery.

 

 

Edited 2 September, 2021 by FrankNicklin

[ChoonDoode]

1 hour ago, FrankNicklin said:

I had this issue only last week. Replaced the battery and the fob would not work. I took the new battery out a few times, even replaced the old battery and it would not work.

 

I then cleaned the contacts inside, and reseated the battery making sure it is fully seated and not at an angle. Been working fine ever since.

 

This is the second time I have replaced the battery in the same fob and the first time went off without a hitch, but the second time was a bit troublesome.

 

If the red light on the fob isn't flashing, its not a sync issue, but the fob battery.

 

 

 

Hmmm, I've checked the contacts. They do seem to be fitting around the battery ok.

 

Just a bit annoying as it was a case of it worked with the old battery and then stops with the new one in. 

[varaderoguy]

humm....do you have KESSY (keyless start and open)?  Your car being a VRS and all that jazz.

 

You should not keep Keys 1 and 2 together under any circumstances.  They will interfere electronically with each other and cause faults and drain the CR2025 batteries really quickly.

[NZ100]

On other posts on the same subject, people talk about cleaning the battery before putting in and checking voltage as well.

I've had batteries from ebay that do work and some that don't. Try another battery. 

[ChoonDoode]

11 hours ago, varaderoguy said:

humm....do you have KESSY (keyless start and open)?  Your car being a VRS and all that jazz.

 

You should not keep Keys 1 and 2 together under any circumstances.  They will interfere electronically with each other and cause faults and drain the CR2025 batteries really quickly.

 

No it's just a normal key. I don't trust keyless entry.

 

11 hours ago, NZ100 said:

On other posts on the same subject, people talk about cleaning the battery before putting in and checking voltage as well.

I've had batteries from ebay that do work and some that don't. Try another battery. 

 

Tried 3, which includes the original dying one. The battery which is currently in the working fob was the first one I tried in the duff fob. This is working fine and no error messages come up on the dash

[skomaz]

If you've tried three then its likely an issue with the contacts not making contact with the battery or a bad connection on the fob (eg one of the battery contacts having broken loose from the circuit board).  I'd start by tweaking the contacts and bending them out a bit to make sure they push against the battery.

[stanian]

I've had this a couple of times also, I have switched out the batteries and new one wouldn't work, checked voltage with a multimeter and found sometimes even with a higher voltage and newer battery it still wouldn't work. Mine it would appear is very fussy about the batteries, didn't like the Panasonic ones from Amazon, bought quality branded ones like duracel and been ok since.

 

[ChoonDoode]

3 minutes ago, stanian said:

I've had this a couple of times also, I have switched out the batteries and new one wouldn't work, checked voltage with a multimeter and found sometimes even with a higher voltage and newer battery it still wouldn't work. Mine it would appear is very fussy about the batteries, didn't like the Panasonic ones from Amazon, bought quality branded ones like duracel and been ok since.

 

 

I've got Duracell batteries. The other fob has one in and it likes that.

 

Don't honestly know what the score is. I've ensured the contacts are touching it. So I'm at a loss at the mo

[FrankNicklin]

I’ve only ever used cheapies from Amazon or £1 shop and never had an issue other than my last post. Just fiddled with connections and the seating and all was ok.

[bouff34]

There is another thread somewhere. Several people, myself included have used CR2032 batteries. They are marginally deeper but still fit ok and they seem to solve the issue...

[ChoonDoode]

Quick update on this.

 

So I was able to 'borrow' a 2032 battery from an old motherboard I had laying around and the fob was still not working. That battery was pushing out 3.05v, so I was confident that was working.

 

Back to the fob. I'd already tried 'bending' the contacts, but I've used a Dremel polishing bit just to remove a bit of surface on both the positive and negative contacts and hey presto, jobs a good un.

 

I'd assume because the battery had been out for a couple of weeks was the reason I needed to resync it with the car.

 

Just a bit baffling having to go through that rigmarole.

[skomaz]

In my experience most 'new' CR batteries push out about 3.4v and kessy fobs stop working as kessy fobs at around 3v.

[ChoonDoode]

Just glad mines a normal fob and not a Kessy one. They can sometimes seem to be a bit more problematic.