The-T-Bar MGF Forum

There are a couple of reasons that you might want to change your alarm fob batteries.

It is actually part of the service that the battery gets changed every 15k miles (or 12 months) on a TF). More usually though, the first time you will even think about the fob battery is when the fob starts playing up. If you are lucky, you will notice that the range of the fob is getting less and less, or that the operation is a bit erratic. So, stop putting the fob against your head and standing on one leg and invest a couple of quid in a new fob battery.

The battery is common on most fobs and easy to get hold of.

It is a CR2032 and is a 3V battery.



There are different types of fob, but the two I have are the round type and the square type (technical terms). If you have anything else then the procedure will be similar.



The round type is the most complicated, but is still easy.

On the rear of the fob there is a little recess



Which is just the right size for a screwdriver blade



Push the screwdriver into the recess and turn the screwdriver. This should release the lower cover.



Which can then be removed.



Revealing two little plastic clips on the sides which you can carefully unclip with the screwdriver.



This allows the fob to open up revealing the circuit board and battery



Now use the screwdriver to lever the battery out of the holder, noting which way round it is. Positive is the side with the writing on and faces down.



Replace with a new battery



Clip the two halves of the cover back together



And push the lower cover back on, making sure it is the right way round.





And that is it


The older, squarer, fob is easier to do.



If you look around the edges of the fob you will notice a join that goes all the way around the edge.



Push a flat bladed knife into the join



And twist, forcing the 2 halves apart. Be careful here not to deform the plastic



Once apart, you will see the battery held in a metal holder.



Slide the battery out of the holder, noting which way the battery sits. The positive side, with the writing on, faces you.



Replace with a new battery and simply push the 2 halves together until they click and you are done.


One thing worth mentioning at this point is the fob re synch procedure.
It has never happened to me yet, but if the fob fails to operate it may be down to the fob becoming out of sync with the alarm unit.

To re sync the fob, make sure the car is unlocked and press either of the fob buttons 4 times until the locks operate.

The battaries are dead cheap on eBay.

de sync normally occurs if you leave the battery out for to long and the fob becomes discharged.

Nice one, Clive!

Nice guide for the newbies but there's a safer way to open the square fob without risking deforming the edges of the case - just where the ring attaches there's a slot between the two halves designed to put a knife/slim screwdriver in to - then just pop it apart!

What happens if the fob gets de-synced. Mine is flat so switched to the other until I can get a battery - just not got round to it for a few weeks though, so I suspect mine will have De sync'd.

How do you get it back in sync with the alarm......?

Thanks all
Gary.

You just need to repeatedly press the lock button until the central locking works.

I have two fobs and one is a spare that only gets used once in a blue moon, but after a couple of presses it works OK.

David Aiketgate wrote:


The "book" says that you have to discharge the fob after taking the old battery out by pressing both buttons for 10 seconds, insert new CR2032 battery and press 4 or 5 times near the car to restet the rolling code.

Added a couple of explanatory videos to the original picture guide above.