Keyless unlock doesn't work.

ProfessorX5 · #1 11-29-2013, 11:12 PM

At first I thought maybe the key fob needed a battery, but I heard they don't have a battery, but instead have a capacitor, so the problem is elsewhere. Any clues?

Not a huge deal, but if I can find a way to diy it, I'd love it.

puddinboo · #2 11-30-2013, 12:06 AM

are both keys not unlocking or just 1 ?there is a rechargeable battery in the key, it charges through the ignition switch.

ProfessorX5 · #3 11-30-2013, 12:11 AM

Just one key. If it's rechargeable it's either not recharging or something else is wrong.

Gregory891 · #4 11-30-2013, 01:51 AM

It can be the battery in the switch, in this case have the guy in California (GM5 repair) who is very experienced at replacement, sort his for you. I can recommend him.

The other thing is the FZV antenna module (receives and process the key signal). In my case it was the FZV module. I found a good, used module and after replacement - my remote keys work. Make sure you check your FZV module, as there are different frequencies used depending on where you are in the world.

Qsilver7 · #5 11-30-2013, 01:54 AM

Quote:

Originally Posted by ProfessorX5

...I heard they don't have a battery, but instead have a capacitor...

Here's some info that may help clarify some confusion...some of it was also discussed in a thread you were in the other day...perhaps you didn't go back after your last reply in that thread and missed some of this info:

ProfessorX5 · #6 11-30-2013, 09:56 AM

Neat... so maybe it'll work once recharged (I haven't driven it much yet). If not, I'll check the FZV. BTW, I found this handy article, which might prove useful for future readers of this thread:

BMW Key Fob/Remote unlock repair

Thanks for the input, guys. Looks like I have a few projects lined up for the spring

puddinboo · #7 11-30-2013, 01:01 PM

Quote:

Originally Posted by ProfessorX5

Neat... so maybe it'll work once recharged (I haven't driven it much yet). If not, I'll check the FZV. BTW, I found this handy article, which might prove useful for future readers of this thread:

BMW Key Fob/Remote unlock repair

Thanks for the input, guys. Looks like I have a few projects lined up for the spring

I had 1 key that didn`t work so I openned it up check battery , batt was good ,the little switch for unlock button fell apart . so after that I just put that key back together and I`ll use for a spare if I ever need it to start the sav. long story short I ened up buying a key from the stealer for 220.35 including hst note you have to program all keys at the same time.

Qsilver7 · #8 11-30-2013, 10:46 AM

If you have a battery charger...you can hook it up to the jump start posts in the engine bay, then insert your remote key into the ignition and turn it to POSITION 1...leave it there overnight (for up to the 30 hours needed to fully charge your key's battery).

The battery inside the key only charges when the ignition is in KL-R (position 1) or KL-15 (position 2) or KL-30 (position key returns to once engine has started)...using a battery charger hooked up to the jump start posts....prevents the car's battery from draining (which you don't want to happen with the key in the ignition...doing so has been known to kill the key).

Helihover · #9 11-30-2013, 10:56 AM

Our X is mainly her car. My wife doesn't work and uses it mainly for short trips to cart the kids around. Recently the key fob (and what does fob mean?) started acting up. I figured it was a weak battery do to quite a bit of use with not that much charging time. Last Saturday we went matress shopping and spent the majority of the day driving around and not using the remote. That night it worked great, couple days later, back to normal. I will replace the battery first as this is what I think it is and it only cost about 5 bucks and around 30 minutes of my time.

oldskewel · #10 03-03-2017, 04:39 PM

Quote:

Originally Posted by Qsilver7

If you have a battery charger...you can hook it up to the jump start posts in the engine bay, then insert your remote key into the ignition and turn it to POSITION 1...leave it there overnight (for up to the 30 hours needed to fully charge your key's battery).

The battery inside the key only charges when the ignition is in KL-R (position 1) or KL-15 (position 2) or KL-30 (position key returns to once engine has started)...using a battery charger hooked up to the jump start posts....prevents the car's battery from draining (which you don't want to happen with the key in the ignition...doing so has been known to kill the key).

THIS WORKS!

Thanks for the tip. I had some flaky remotes and one dead one, searched high and low, and this was the only true charging method I found that did not require enduro driving. Before doing this, I tried putting all remotes on the same key chain, and drove like that for a couple of weeks, but I guess not enough charging time there. Two fobs were still flaky, and the one diamond key was still dead (still started the car, of course).

I did Qsilver7's tip last night, with the diamond key in the ignition, turned to ACC (I), with the two flaky fobs rubber banded on either side of it. Car charger hooked up to the engine bay charging points to prevent battery from dying.

So today, after overnight charging, the two previously-flaky key fobs (cut from eBay diamond keys) are rock solid again. The diamond key is still dead as a doornail, so I guess it will be going in for surgery soon.

Question - before taking the diamond key apart, is it worth trying to reprogram all remotes? I would think that since all 3 other remotes work fine, and one works not at all, that it is not a problem on the car-side.