getting a second (and third) remote entry solution

[workingonit]

from another thread

Originally Posted by oldskewel

If you can't get keyless entry to work, and rely on the mechanical key in the door to lock and unlock, you can be sure the lock cylinder will fail within about a year of daily use, leaving you in a predicament. <== and that's exactly what happened to me.

A cheap and easy solution to the need for a remote functionality is to buy a used genuine BMW diamond key on eBay (I bought 3x for $15 each when I got my car). You can then cut the key blades off (useless on your car), reprogram the keyless entry functionality, and use them as key fobs. You'll need to find a convenient way to keep them charged. When you go to start the car, the immobilizer system will see the RFID chip in your actual key as well as the old one in the eBay fob, and will just ignore the eBay one, allowing the car to start. <== All that is exactly what I've been doing since 2014.

I took oldskewel's advice seriously, and bought two generic diamond keys on eBay, for $16 (for two). They arrived just now, batteries already installed (CR2032, not rechargeable) and sealed. It took me a minute to program them to work my remote functions.

Now, if I bump/crush/demolish my original remote diamond key (which I eventually have done to all my plastic remotes), I can still gain entry without using the physical lock on the door. When I put a new rechargeable battery into my original key, I severed a wire trace inside...I fear that it'll break loose again, so I wanted a backup remote on me at all times. I've never bent/broken/lost any of my physical keys in 55 years, so that wasn't a concern.

This should gain me some time to actually order a true BMW NA diamond key, but I've got a noisy clutch fan that worries me (though the viscous clutch feels good & just tight enough, I don't want blades coming loose just now), so an electric fan conversion is my first priority.

I have two trucks with clutch fans ('04 Chevy 2500HD with 135k miles, and a '98 GMC with 185K miles), but they're still in great shape...but I worry about the X5. I have previously added electric fans on most of my previous 20+ vehicles, either as primary or secondary cooling fans, auxiliary fans for a dedicated transmission cooler, or in the case of my now traded (for the X5) '66 Chevelle, all three types. I'll probably do the fan conversion soon.

[mike325ci]

Good idea and info. I also broke my fob trying to replace the Panasonic battery, desoldered something...

Mind sharing where you are finding them that cheap? They seem to be just the shell no PCB, or at around $30 a piece on eBay....

Sent from my SM-N986U using Tapatalk

[workingonit]

Originally Posted by mike325ci

Good idea and info. I also broke my fob trying to replace the Panasonic battery, desoldered something...

Mind sharing where you are finding them that cheap? They seem to be just the shell no PCB, or at around $30 a piece on eBay....

Sent from my SM-N986U using Tapatalk

I see that the price went up $4 USD, and the free shipping by DHL Ecommerce took a week, but it's still two keys for about $10 each. The seller includes recommended locksmiths to make the keys work in the door and ignition, but I just got them for the remotes.

https://www.ebay.com/itm/19313897449...g:nzcAAOSweRpd

[oldskewel]

Glad to see the plan is working for you.

So that solution of buying two new cheap Chinese eBay fobs is the newer substitute for my older solution of buying old used Genuine BMW diamond keys on eBay for about the same.

I think for the purposes of the plan, the two are equivalent. They solve the problem of keyless entry, and that is it. But unlike the used genuine key solution, you could have the key blades cut to match your mechanical locks in the driver's door, ignition, and glove box. ...

But there is virtually no way that they will ever be able to solve the EWS problem to allow you to start the engine. The eBay seller saying to take it to a locksmith for that is not really practical. I won't say it is impossible, but probably not cost effective to work around the BMW EWS system.

That original diamond key you already have will still solve that EWS problem for you, even if the keyless entry no longer works on it. So something to consider is (first don't lose it or consider it worthless even if it falls apart) to keep it in the car permanently for the sole purpose of keeping EWS happy. I don't know how close it has to be to the ignition lock clinder, but you could consider installing it on the inside of the steering column panels in there. That would effectively bypass the EWS system, and you could use as many $10 keys as you want, having the blades cut, etc.

The EWS system is not confused by seeing non-conforming EWS chips in addition to a valid one. That's how my solution works = new Genuine BMW valet key (with valid BMW-programmed EWS chip) + old Genuine BMW diamond key (fob with blade cut off, with invalid BMW EWS chip for a completely different BMW). When running my PASoft scanning software, I'd see EWS warnings showing an invalid chip present, so it knows it's there, but will not stop it from allowing the engine to start, as long as a valid one is there as well.

I don't know whether the EWS interrogation requires the fob to be powered with a battery. So if your battery (the rechargeable Panasonic 3V) battery in the genuine diamond key is dead or the circuit has broken, but the EWS is intact, it might or might not work. The cheaper Genuine BMW valet keys do not have any battery; the interrogating signal coming from the antenna surrounding the ignition cylinder also instantly powers the circuit so it can receive and respond to the coded signal. So that shows it is possible, but I'm not completely sure yet whether the EWS in a diamond key has the same capability to work without a battery.

[Effduration]

Hey Oldskewel, Is there a convenient way to charge key fobs outside of the car?

I like the idea of used genuine key fobs as extra remotes, but I remember reading that if they are hanging on a key chain they aren't close enough (or are not positioned correctly) to be charged by the induction charging of the ignition.

I have heard that certain phone and toothbrush chargers can charge our fobs, but haven't see a definitive solution.

[workingonit]

If I may answer this question, this is what I bought, and it works.

[Effduration]

Originally Posted by workingonit

If I may answer this question, this is what I bought, and it works.

Thanks for this...

The two Ebay remotes you bought have non-rechargeable batteries. Any idea how long they might last? A year or more ?

[workingonit]

Assuming the batteries were freshly installed prior to shipping (in China, before shipping to NJ, or installed in New Jersey??) probably <3 years. I've had seldom-used 3V lithium batteries last up to six years, but on remotes used daily, 2-2.5 years. In any case, I've cut my original key open before...these should be much the same. At $10 apiece, I'll not worry about damaging them, so much.

[oldskewel]

Originally Posted by Effduration

Hey Oldskewel, Is there a convenient way to charge key fobs outside of the car?

I like the idea of used genuine key fobs as extra remotes, but I remember reading that if they are hanging on a key chain they aren't close enough (or are not positioned correctly) to be charged by the induction charging of the ignition.

I have heard that certain phone and toothbrush chargers can charge our fobs, but haven't see a definitive solution.

I analyzed all that when I had the fobs opened up when I put in new rechargeable batteries, covered in this thread:

https://xoutpost.com/bmw-sav-forums/...r-options.html

Specifically on the recharging ...
Prior to doing the surgery, my solution was to masking tape all 4 of my fobs (one original diamond key in the ignition, plus the 3x eBay fobs) together, with the diamond key in, and the other fobs close enough to optimal position to take in the charge. I'd put them in the ignition, with the key to ACC, with the car on a battery charger so it would not run down, and overnight the fobs would be well charged. I found I could easily go a year or more before I needed to repeat that.

But when I had things opened up, I thought I'd try to experimentally verify which of the various chargers would actually work, of course wanting to use a charger I already had.

Post #14 in that thread: https://xoutpost.com/1183412-post14.html

Post #19 https://xoutpost.com/1183483-post19.html

I measured the fob battery voltage in the presence of my toothbrush charger (failed to charge), and then my son's iPhone charger, which worked perfectly, steadily ticking up at about a mV per minute, leading to an end to the experiment. So that's what I do now to keep them maintained without needing to do the more manual solution above.

As said there, the iPhone charger is a Belkin F7U027
https://www.amazon.com/Belkin-Boost-...075M59ZB7?th=1
https://www.belkin.com/us/support-ar...icleNum=274455

with some details in there about the green light on the charging pad. If not measuring the fob battery voltage, I would think it was not working, based on the green LED.

BTW, @workingonit had asked me earlier about where these fobs were on eBay. From a quick look, I could no longer find used Genuine BMW fobs on there, which were plentiful back in 2014 when I got mine. I can see that these NEW non-OE ones are so cheap, do the job, and have the convenience of replaceable batteries, so maybe that led to the old ones going away. But the BMW ones are pretty amazingly built on the inside, so I'm happy I got mine when I did.

[wpoll]

Originally Posted by oldskewel

... I don't know whether the EWS interrogation requires the fob to be powered with a battery. ...

... So that shows it is possible, but I'm not completely sure yet whether the EWS in a diamond key has the same capability to work without a battery.

It doesn't require the battery at all - as you indicated, the EWS transponder is powered by the RF field around the ignition lock.

BUT... the diamond key EWS transponder is built on the same PCB as the rest of the key-less entry circuit and relies on some of the components on that PCB (antenna coil, rectifier, capacitor, transponder I.C. etc.) so any damage to the PCB may result in a non-working EWS transponder.

Other transponder solutions (as used in some BMWs, V.W.s etc.) are based on a self contained transponders I.C. or micro-device and can be moved from key to key.