Only driver door opens, other 3 locked.

Farintosh · 06-20-2016, 04:16 PM

Hey Everyone!
The car on question is an 86' 735i but I'm looking for a fast answer an know you guys are always on the ball and generous.

The problem: Suddenly I can only open the driver door, other 3 have tabs pushed down in lock position. Can't pull them up or open them with a key, even on the passenger front the key only turns about half the movement needed to unlock the door. Trunk works fine. I just picked this car up and it never had power locks but all 4 doors worked until today. I feel like I'm missing something obvious.

Could it be some form of double locks? Apparently a group of kids were playing around the car when I was out?
Have a friend coming over to potentially buy the car so I'd love to get it sorted.

Thanks in advance for your time!

Blackedout95 · 06-20-2016, 04:34 PM

Off the top of my head on an 86 ... hhhmmm my guess would be if no signal is being sent to ALL other doors and even gas door? I would put money on the general module or relay module as it were.

Now in saying that with enough time the passenger should work with the key but could be stiff.

Best bet, locate your General Module/Relay and swap it.

I accept donations of praise only LOL

Farintosh · 06-20-2016, 04:40 PM

Quote:

Originally Posted by Blackedout95

Off the top of my head on an 86 ... hhhmmm my guess would be if no signal is being sent to ALL other doors and even gas door? I would put money on the general module or relay module as it were.

Now in saying that with enough time the passenger should work with the key but could be stiff.

Best bet, locate your General Module/Relay and swap it.

I accept donations of praise only LOL

Thanks for the quick response!

That's probably one of my issues, the power locks never worked, but maybe the double locks still do somehow but not enough to unlock?

I figured that the passenger side door should still unlock if it's the relay, the key just won't turn enough and I can't pull up on the tab like I can on the driver's door, again only goes about half the way.

Going to show the car now, thanks again,
Much praise!

Blackedout95 · 06-20-2016, 04:44 PM

Oh ya the pass door should open with key BUT because that is a rare thing to be used over 30 years expect it to be very stiff!

Try looking at contacts and cleaning etc before swapping them if you want but I have a feeling that when one part affects all the others at the same time, its the part you need to look at first, could be wrong though just my experience.

Ceeker · 10-27-2016, 04:31 PM

There is no other potential problem. Not that it matters at this point in time but I'm bored and thought I would post. lol

Sometimes the micro switch fails in the drivers door like happened in my e30 vert. Aside from the passenger door actuator missing the the faulty central control unit. Even after replacing the bad module and installing the passenger actuator. I still couldn't get the locks to lock or unlock. Narrowed it down to the micro switch tab not touching the tumbler on the lock cylinder to signal the CU to lock the doors. The tab floats on the cylinder and it has a hump where it pushes the tab up to signal the switch to signal the CU. I checked to see if the lock cylinder was worn but it was replaced by the previous owner. it took me a while to isolate the issue as I've never encountered this problem with the locking system before.

Solution: I bent the chrome level up a bit on the micro switch enough so when I turned the lock cylinder to lock or unlock position it signaled the locks to sync.

Farintosh · 10-27-2016, 04:59 PM

Quote:

Originally Posted by Ceeker

There is no other potential problem. Not that it matters at this point in time but I'm bored and thought I would post. lol

Sometimes the micro switch fails in the drivers door like happened in my e30 vert. Aside from the passenger door actuator missing the the faulty central control unit. Even after replacing the bad module and installing the passenger actuator. I still couldn't get the locks to lock or unlock. Narrowed it down to the micro switch tab not touching the tumbler on the lock cylinder to signal the CU to lock the doors. The tab floats on the cylinder and it has a hump where it pushes the tab up to signal the switch to signal the CU. I checked to see if the lock cylinder was worn but it was replaced by the previous owner. it took me a while to isolate the issue as I've never encountered this problem with the locking system before.

Solution: I bent the chrome level up a bit on the micro switch enough so when I turned the lock cylinder to lock or unlock position it signaled the locks to sync.

Thanks for the input Ceeker, I've actually been out of town so I haven't really looked at the car, back next weekend though. I had someone tell me the electric locking system is controlled by a central electronic control unit that is mounted below the left front speaker in the driver's side foot-well but in my car I only found the cruise control module there. Do you know where I should be looking for the central unit on an 86' e23? I feel like it must be the module with all 3 doors going at once.

Blackedout95 · 10-27-2016, 05:12 PM

http://bmwe32.masscom.net/johan/elec.../rearseat.html

General and keyless module under rear seat.

Blackedout95 · 10-27-2016, 05:12 PM

oops double post.

Farintosh · 10-27-2016, 05:33 PM

Quote:

Originally Posted by Blackedout95

http://bmwe32.masscom.net/johan/elec.../rearseat.html

General and keyless module under rear seat.

Awesome, I noticed this is for an E32; it's the same in the e23? Just pull up the rear seat and I should find this?

Blackedout95 · 10-27-2016, 08:23 PM

Oh ok wasn't sure how late your 86 was.... if not under back seat then try drivers side footwell, just above hood latch release, small black box, rectangular cant miss it right above release latch if I recall. Just remove the kick panel. btw there is a fuse for that controller don't forget to check it

Farintosh · 11-02-2016, 02:36 PM

Quote:

Originally Posted by Blackedout95

Oh ok wasn't sure how late your 86 was.... if not under back seat then try drivers side footwell, just above hood latch release, small black box, rectangular cant miss it right above release latch if I recall. Just remove the kick panel. btw there is a fuse for that controller don't forget to check it

You were spot on with it being in the drivers side footwell.
Here are a few photos.
http://imgur.com/a/0zTVL
I could hear some rattling inside the unit but I didn't want to crack it open and make things worse as I have a few potential buyers. If i go to get some parts I'll grab the module and see if that does the trick. I checked the fuses associated with it and they all looked good; swapped a few for good measure to no avail. I believe fuse 27 is the one associated with central locking.

Blackedout95 · 11-02-2016, 05:06 PM

Glad to hear you found it, keep us posted after all it was still just a possibility right.

PinkieMoscow · 01-26-2017, 02:11 PM

Most likely the rear module, common issue with e46's too.

Farintosh · 06-03-2017, 01:53 PM

Well I finally got some time to pull the car into the shop and take a look, about 10 minutes later the car was fixed!
Ceeker sent me in the right direction after mentioning the microswitch inside the drivers door. I pulled off the panel and found the connection which must control the double locks wasn't grounded properly. For now I just disconnected it altogether so I still have power locks but don't have to worry about the double locks tripping again.
I don't know how many bmws share this system but I thought I'd make a quick video in case anyone runs into this issue again; I see another 735i out in kitchener with the same issue right now. You can skip to 2:18 to avoid how to pull a door panel.

https://www.youtube.com/watch?v=bhxCBtiaDzU