[xeasi]

I have quite a peculiar problem. The Comfort Access system on my F10 works partially. I can start the car no problem with the key in my pocket etc, but lock/unlock does not function on any of the doors.
Scanning with ISTA gives no fault codes on the CAS module, but when checking the Comfort Access state of all doors, they show "not operated" and occasionally briefly flashing "not available".

Pulling out all the door handles I noticed that the old owner had covered the CA plugs with electrical tape. I pulled those off and plugged the CA plugs back in but nothing changed. ISTA still says CA for all doors is "not operated" however I can start the engine with the key in my pocket and if walking away from the car with the key, the antenna will detect that i'm going out of range.

Anyone have any idea what might be causing this? Could it be related to a software bug due to old owner pulling out the CA plugs and now it needs resetting somehow?

Thanks in advance.

[CrippledLucifer]

Maybe you just have faulty door handles? I recently had the change the door driver side door handle on my 2016 since it wouldn't unlock or lock the car. While waiting for the new one, I too disconnected the CA wire and left the LED wire plugged in. No idea if that's the reason why the PO of your car disabled the CA wires. As soon as I replaced the handle, the lock/unlock issues went away but now my rear drivers side door has started to display the same bug. The door handles appear to be a fairly frequent problem on these cars.

[xeasi]

That's what I'm afraid of as well. Hopefully someone might have an idea on how to identify a faulty door handle using a multimeter or such? Or is it just a case of buying a new one and hoping for the best?

[Qsilver7]

Since the electrical plugs have been pulled by a previous owner…make sure that they didn’t pull fuses associated with CA, too.

And just an FYI…the remotes are not “one-trick-ponies”…they have multiple things going on. For example, the ability to start the car and the ability lock/unlock the car are two different things. Similar to you and your neighbors…you all turn down the same street, and may pick up your mail at the same location…but you all turn into different driveways and enter your own garages and houses.

The central locking feature of the remote key is powered by the battery inside the remote and sends a radio signal to an aerial (when the lock/unlock buttons are pressed) which then sends that info onto the CAS module…and it also sends out signals picked up by proximity aerials for the door handle lock/unlock, and the newer version of CA has the lock/unlock while approaching or walking away.

The starting feature of the remote does NOT use the battery inside the key…it uses induction to power the communication with the DME & CAS modules.

All the above was mentioned to help not get bogged down with diagnosing systems that are working and including them with the issue that you’re having.

Good luck in narrowing down the culprit.

[CrippledLucifer]

Originally Posted by xeasi

That's what I'm afraid of as well. Hopefully someone might have an idea on how to identify a faulty door handle using a multimeter or such? Or is it just a case of buying a new one and hoping for the best?

In my case the key battery warning started showing up even though the battery was brand new. Also the car would constantly keep trying to unlock itself when I was in range of the door handle. It didn't matter if I used CA or not, the doors would unlock on their own like newer BMW models lol. Kind of wish we could code that proximity unlock/lock on our cars. It is very convenient.

[Hoa]

The sensor that detect your key to start is separate. There are two in the center console.

I'm not sure about the CA door handle issue. They probably disabled it because they had the issue you are experiencing now and didn't know how to fix it or spend money on it?

[xeasi]

Bought a new door handle from dealer. Disconnected all the other door's CA plug. Still not functional. Then discovered that ISTA actually has a diagnostic function to check the activation of the unlock/lock signal of the door handle. ISTA shows that signal is received but door is still not locked/unlocked.
Fortunately ISTA also has a function to check the functionality of the aerials which all came out good. This leaves me to believe that the cause could be my faulty contact-free tailgate upper sensor. Reading the functional description of the contact-free tailgate shows that it is forcefully connected to the CA system which in my theory would act in the same way as a faulty door handle: jamming the CA system with a faulty signal.
Dealer will take my car in 3 weeks. Will keep you guys updated.

EDIT:

Previous owner had installed a different CAS module which was not compatible with Comfort Access. Car didn't show any fault codes indicating to this. Dealer diagnosed it by comparing actual module HW version to nominal HW version. New CAS module installed, Comfort Access is working.

[mickeyvalentine]

Just started having this issue as well. I’m glad the OP was able to figure it out but fingers crossed my issue isnt that bad. Great info here guys. Thanks.





Side note:

Originally Posted by Qsilver7

The starting feature of the remote does NOT use the battery inside the key…it uses induction to power the communication with the DME & CAS modules.

While I respect you Qsilver, I don’t believe induction would be a player here. That implies a cut key is being inserted into the ignition in the column (like the e38 works) or the keyless FOB is being held near the column where the glyph of the a key is located. Otherwise the key can be thrown in the back seat under some blankets and the vehicle will still start with comfort access. Which would require battery power.

[Qsilver7]

Originally Posted by mickeyvalentine

While I respect you Qsilver, I don’t believe induction would be a player here. That implies a cut key is being inserted into the ignition in the column (like the e38 works) or the keyless FOB is being held near the column where the glyph of the a key is located. Otherwise the key can be thrown in the back seat under some blankets and the vehicle will still start with comfort access. Which would require battery power.

Thank your for the respect (and I do appreciate those words & sentiments). It's dialog like this that we all learn. You raise a very good point.

Based on the bolded text in your quote above...I think we are on the same page. If you remove the battery from the remote...it will still start the car if near the vicinity of the "glyph" on the side of the steering column....there is a electromagnetic induction field around that area...and when the remote is near it, the engine can be started if the START button is pressed and your foot is on the brake. The ability of the remote to start the car without a battery is due to this induction field where the remote, CAS, and ring aerial (used to be called ring antenna back in the e38/e39 era) communicate with each other sharing their encrypted identification that allows the engine to start.

See info below that discusses the ring aerial and how induction allows for the car to start. If you move the remote too far away from the induction field, then the car won't start. I've also seen a warning when the remote is moved too far away from this induction field...just as mentioned in the info below.

FYI: ID transmitter refers to the remote fob in info below