anti-theft question

[wengenstein]

A few hours ago I went to get in my car and found that I couldn't de-activate the alarm with my key (I have a 12/94 prod 540). The key worked alright less than an hour before but this time it was a no-go. I ended up having to pull the fuse for the anti-theft system (the one in front of the EBox under the rear seat on the driver's side) to get the friggin alarm to shut up;



(credit goes to shogun for posting these pictures in another thread)

My question is this, what will I need to do to get things back to normal? (replacing the fuse just sounds the alarm again) Is it usually just a low/dead battery in the key that's the problem or will I end up having to visit a dealer to get this straight?

[shogun]

Probably can't help you that much. I have never ever in 11 years I own the car used the alarm or anti-theft device. I even do not have an insurance for the case that someone steels the car.
1. Too expensive for an imported car of the (new) value of about 160K $ at the time when it was imported (we still had then 20% luxury tax on such imported items).
2. Probability that the car is stolen is pretty low in Japan.

Isn't there this info in the owners manual to remove the battery and etc to kill the alarm?
Just another info in case the (false) alarm goes on suddenly when the car is parked
http://members.roadfly.org/smoothy/False%20Alarm.pdf

[Qsilver7]

does your key have a red LED light in it? if it does...is it illuminating when you press the buttons? If you have to change the battery...do it within 60 seconds...if the remote is without a power source for over 60 seconds...it will loose its programming and you'll have to reinitialze the key!

Also, as you stated...you might want to check your battery. If you've unlocked your OBC you can do TEST #9. A consistent reading between 10.5v-11.5v (engine not running) indicates a failing battery.

Did you stick the key into the ignition and turn it to position 1 or 2 when the alarm went off? I believe that is what's in the owners manual for when you have to manually unlock the door when the alarm has been set.

If you don't have an owner's manual...here are 2 excerpts from the e38 owner's manual which has the same DWA/EWS (anti-theft/immobilizing) system as the e34 540i.

Emergency Deactivation of the System



Key (note the text within the red lines)

[wengenstein]

The light still comes on. (which is one of the reasons I'm so confused )

And I did read the part in the manual where is says leaving the key in position 1 or 2 would deactivate the alarm but it didn't work when I tried it. Maybe I'll give it another shot tonight.

does your key have a red LED light in it? if it does...is it illuminating when you press the buttons? If you have to change the battery...do it within 60 seconds...if the remote is without a power source for over 60 seconds...it will loose its programming and you'll have to reinitialze the key!

Also, as you stated...you might want to check your battery. If you've unlocked your OBC you can do TEST #9. A consistent reading between 10.5v-11.5v (engine not running) indicates a failing battery.

Did you stick the key into the ignition and turn it to position 1 or 2 when the alarm went off? I believe that is what's in the owners manual for when you have to manually unlock the door when the alarm has been set.

If you don't have an owner's manual...here are 2 excerpts from the e38 owner's manual which has the same DWA/EWS (anti-theft/immobilizing) system as the e34 540i.

Emergency Deactivation of the System



Key (note the text within the red lines)

[digitaldragon03]

I had this exact problem about a month ago. Someone told me that i had to short the battery, replace the fuse, then charge the battery again. This would reset the computer and thus the alarm wouldnt remember that it was being stolen before taking out the fuse. I havent tried this yet, but i think you should give it a shot. Did your OBC go out as well? Im never using the alarm again, but i think its worth trying to do the reset procedure just to get your OBC back.

[Tiger]

I believe the trick was to turn key to on position (Position 2) but do not crank engine... it will reset itself in within a minute. It is stated in the owner's manual.

[biondani]

I had this exact problem about a month ago. Someone told me that i had to short the battery.

DO NOT JUST SHORT THE BATTERY. What you would need to do to reset the computer is to disconnect the battery and connect the two battery leads together to drain the residual power from the car. Shorting out the battery will lead to some pretty nasty burns if it doesn't explode.

Ian

[wengenstein]

The OBC and the alarm system are tied together, pulling the fuse on the control box will prevent the OBC from operating. I've tried disconnecting the battery (rather than connect the leads I just left it disconnected for 1+ hrs) but not with the alarm fuse removed. I'll give that a try too. I was just about to go out and mess with it some more when I stopped to take a look at the forums..

I had this exact problem about a month ago. Someone told me that i had to short the battery, replace the fuse, then charge the battery again. This would reset the computer and thus the alarm wouldnt remember that it was being stolen before taking out the fuse. I havent tried this yet, but i think you should give it a shot. Did your OBC go out as well? Im never using the alarm again, but i think its worth trying to do the reset procedure just to get your OBC back.

[wengenstein]

I bought a new key and attempted the reset procedure. It didn't work. So I made an appointment with a local dealer and paid $99 to have them scratch their head for an hour and pull the codes. They believe that the micro switches and or the front two door lock actuators need to be replaced.

Have any of you guys seen this sort of problem before, the door locks continuously tripping the alarm? It's been a while since I looked at the wiring diagram for the alarm system. Also, if I don't want to spend the time/effort in fixing the door locks, how easy would it be to at least get the OBC back? How difficult would it be to bypass the alarm controler to get the OBC functional again?

[Javier]

It was removed when you pulled out the fuse to silence the alarm. Best way to do so is to pull out connector X335 from the DWA module (the one you removed the fuse from). X335 is the black four pin connector (see picture). You need to jump with a fuse (small one, 5 A may be) pin 4 to pin 2. For that, you may buy an ordinary fuse, solder in the pins a couple small wires, and plug the wires in the connector pins (female terminals). Insulate it properly when done.

On the other hand, can not understand wtf have to do the Micro switches or door lock modules with disarming the alarm. May be you would like to pull out all the DMA module connections and test one by one all the signals going in. For that you can use the wiring diagrams link posted by Shogun, diagram 6575.3 is DWA and has enough info to do so if you have the patience and will to check it.

I would have special concern on the Remote receiver module (see drawing 6610.1 in the same link). For it, fuses F18 and F33 are very important. Check specially fuse F33 under rear seat. Absence of light at DWA led in the center of dash may be an indication of a blown F33. If F33 results blown, check the trunk lid hinge harnes for cut or uninsulated wires.



Javier