Central Locking Issue
 

Guys,

My central locking system is acting up. Everything was fine until I drove it at lunch today. When I got out of the car, something happened, but I can't recall what because I got distracted by my turn lights flashing. I thought maybe I had accidentally hit the hazzard button or the turn signal lever. I check those, cycled both, and that stopped the flashers. But then, when I shut the door and tried to lock the car from the remote, I got the single chirp, but no lock actuation. I also tried locking the doors with the key - this will lock one door, but not all like it did before. I spent 20-30 minutes trying different combinations of car-on, car-off, doors-open, doors-closed, lock-unlock, etc. etc. to see if I could somehow get the system to reset itself. No dice. I have searched the archive here for some info, but so far only found a few similar issues, but no solutions.

Any help would be great.

Thanks,
Charles
Car Details: 95 ti black. Alarm/Keyless details: 3 button remote with the little red light and reset swtich on the console and the. (I can't recall what happens when you push that little reset button with a bent paper clip...)

More info...

Windows and Sunroof are not working. Wouldn't normally notice since it's been raining a lot lately, but I checked them to see what was getting power.

Interior dome light not coming on when door is open. Does work when the switch is put in the "on" position. Door chime seems to work correctly too, because it chimes when I open the door with the key in the ignition.

Looking at the Bentley now. Might be able to see what's common to all of these systems - likely the computer... All the fuses in the box under the hood seem fine. Is there a power relay that would serve central lock servos and door/sunroof motors?

Took out the glove box to get to the alarm/keyless control unit. Unplugged and replugged a few times, with no change in behavior. When I push the buttons on the remote, I can hear the relays inside the unit clicking, but not sure if this is the relay to the door locks or to the siren. When i press the window switches, I don't hear any relays at work in the box.

Also spent a while looking through the Bentley wiring diagrams. I was looking for maybe a second fuse (outside of the main power box) or a relay that was the source of the lock and window power, but from the schematics it looks like the power just goes through the box. It's a little surprising though since none of the wires coming out of that box look beefy enough to carry window motor current (most of them look 16-18 guage).

Still looking...

After a lot of internet searching, I thought I had hit on a possibility - the comfort relay. But after more searching and looking at the Bentley, it seems that the comfort relay does not exist on my car (June 95). That function in late 95+ is integrated into the body computer.

Also did a sanity check on all the fuses with an ohm meter. None of them looked blown, but wanted to be sure.

Also saw a post about wire shorts in the trunk harness causing problems. Might go explore that now, but a little skeptical on that one.

Really stumped here... Any help out there?

Not to thread jack but.... My dad is having a related issue with his 92? M42 318i. He changed a fuse and all the doors locked and he can't them open. Keys are locked inside and he even managed to get a hook around the button for the lock nd pull it up but it still doesn't do anything. Sorry not thread jacking ur thread hear just didn't want to make a new thread lol

Sorry I can't help you cc :( good luck though

Further checks didn't reveal any new info... Starting to think that maybe the body computer is broken. May try to take it out and look inside to see if there is anything obvious. Does anyone have a known-good body computer they want to sell?

The comfort relay was added to older cars between the ZKE / central body electronics module and the sunroof, because the ZKE's "comfort" output can't power an older, switch-and-relay sunroof. A newer one-touch sunroof has electronics to monitor the signal and eliminate the intermediate, comfort relay.

The comfort relay was effectively folded into the sunroof electronics on later cars; the ZKE never had one. This distinction may seem pedantic -- until you decide to use its comfort output to power something and discover it hasn't got the oomph.

have you checked bonnet switch and door and hatch switches a fault on one of these will throw out ya central locking