E31 Emergency disarm of alarm system

[tvjake2]

All of SoCalEights would like to thank Timm Meek for his, pretty much awesome website, for it's invaluable reference to the E31 eccentricities and mechanisms. There are many of us that could not survive without it. a truly valuable resource. We sent out this email to our SoCalEights members as a part of our regular helpful hints.
Thanks Tim!

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E31 Emergency disarm of alarm system




All:

I've been having some issues with my alarm system where it will setoff when the temperature gets into the upper 70's or the sun just beats down on the hood. What's happening is that the sensor, integrated into the hood latching mechanism on the right side, seems temp sensitive. Timm on Bimmerforum gave me this hint so I disconnected the sensor and, hopefully, it stops the random alarms from sounding.

On Timm's site (which all of you should know about) is a section that includes the BMW Alarm manual which is very helpful but...it was written for the 1994 cars and my 1997 has a bit of a different setup where the sensor is integrated into the latch at the front.

In addition to all this great info I found an emergency alarm disable process that I thought would be helpful to all of us. Here it is:

Emergency disarming
Emergency disarming It may be possible that the anti-theft alarm system (DWA) can no longer be disarmed in the event of the remote control or central locking systems failing. In this case, the DWA must be disarmed, however, this procedure triggers an alarm.

Procedure:

• Unlock driver's door mechanically and open, an alarm is triggered, the status LED flashes.
• Close all doors, the boot lid/tailgate and the bonnet. Also close the windows on vehicles with window monitoring.
• Switch ignition lock from position 0 to position 1 (terminal R ON), the status LED lights.
• The system is disarmed after a waiting time of 10 minutes has elapsed, the status LED goes out.

• The emergency disarming procedure is terminated if a door is opened or the ignition lock position changed during this waiting period. Emergency disarming is restarted when, after closing the door, the ignition lock is switched from ”0” to ”1”.

This is another helpful note provided you by SoCalEights. Also don't forget.........

Tom Jacobsmeyer
Events Coordinator
SoCalEights
#SoCalEights
Instagram @SoCalEights

[dlove]

found this post - did it work ? how did you disable the alarm sensor ?
thanks in advance !

[tvjake2]

found this post - did it work ? how did you disable the alarm sensor ?
thanks in advance !

Well, it didn't for the issue I seem to have. One of the SoCalEights experts says it is the sensor in the trunk located on the left side of the trunk. It you unplug the connector it will disable the leveling sensor and the alarm should not go off in the heat...I hope.

[Timm]

I didn't see this the first time around - but, thank you very much, and it is always my pleasure!

[EricinConejo]

Maybe this would have worked for me. My alarm started going off randomly. It began after a wash. I disconnect the hood sensor and it was quiet for a year. Then it came back. I disconnected the tilt sensor in the trunk but that didn't help. I read it can also be a window sensor magnet coming unglued. That was about as far as I wanted to troubleshoot so I pulled the fuse under the passenger side sill, so no more alarm. Don't get the cool chirp when locking the car anymore though . I also read that 95 and up have a different siren where the internal battery going bad can cause this. Happy the way it is so no plans to get a new siren.
http://www.frankies-bmw.com/8series/...larm_siren.php
https://www.eeuroparts.com/Parts/177...n-65758383153/

[tvjake2]

Maybe this would have worked for me. My alarm started going off randomly. It began after a wash. I disconnect the hood sensor and it was quiet for a year. Then it came back. I disconnected the tilt sensor in the trunk but that didn't help. I read it can also be a window sensor magnet coming unglued. That was about as far as I wanted to troubleshoot so I pulled the fuse under the passenger side sill, so no more alarm. Don't get the cool chirp when locking the car anymore though . I also read that 95 and up have a different siren where the internal battery going bad can cause this. Happy the way it is so no plans to get a new siren.
http://www.frankies-bmw.com/8series/...larm_siren.php
https://www.eeuroparts.com/Parts/177...n-65758383153/

Ah, good info to have. I've still got to try the sensor in the trunk unplug.

[gon850]

Hi, I need help to locate the tilt sensor. My car has hi fi as an option and I guess that is why I can not see the tilt sensor on the driver side in the trunk. I had all the rear trim removed and it is not visible, left nor right. I can not see it.

Any clues please?

DIS says it is the tilt sensor that triggers the alarm!

[JK840]

My 97 840 started triggering the alarm every time I unlocked the car when I got back for the summer. It hadn't been driven for 7 months. Tried pressing the lock button a second time as a solution. Seemed to work sometimes. I have now disconnected the tilt sensor in the truck and this has solved the issue!

I need to thank Timm, one more time, as well as other cotributors to this thread. Never would have figured this out on my own or found the sensor without the help.

[Bengelbr]

Hi @JK840, I am looking for that trunk sensor in my 97 850CI.. I scoured these threads, procured shop manual PDFs, but didn't find the map to it. Do you have a link or pic by chance?

If anyone else sees this.. She sat in the Florida heat for a few weeks (a lady crunched my passenger door/front panel as I sat at a stoplight.. I am awaiting parts. Just bought her 2 months prior. Pretty devastated but she was getting years of love anyway, just had to reorder the list...) and after a couple of random flashing/alarm light episodes, she won't start. Starter could turn over a jet engine, but no fuel. Replaced fuel pump relay. Checked the other two relays in eBox, solid clicks. BaT seller listed a recent fuel pump rebuild, so I figured the pump will be last stop. This car had an odd journey I think - no alarm sound. The driver door will not lock, though the lock stem does move up/down. Almost like the car was .. neutralized. But I like puzzles..

I tried the method at top of thread (10 minutes in position 1), no dice.
Grateful for any guidance. This community is remarkable.. really fun to see and, hopefully, give something back.

[tvjake2]

Hi @JK840, I am looking for that trunk sensor in my 97 850CI.. I scoured these threads, procured shop manual PDFs, but didn't find the map to it. Do you have a link or pic by chance?

If anyone else sees this.. She sat in the Florida heat for a few weeks (a lady crunched my passenger door/front panel as I sat at a stoplight.. I am awaiting parts. Just bought her 2 months prior. Pretty devastated but she was getting years of love anyway, just had to reorder the list...) and after a couple of random flashing/alarm light episodes, she won't start. Starter could turn over a jet engine, but no fuel. Replaced fuel pump relay. Checked the other two relays in eBox, solid clicks. BaT seller listed a recent fuel pump rebuild, so I figured the pump will be last stop. This car had an odd journey I think - no alarm sound. The driver door will not lock, though the lock stem does move up/down. Almost like the car was .. neutralized. But I like puzzles..

I tried the method at top of thread (10 minutes in position 1), no dice.
Grateful for any guidance. This community is remarkable.. really fun to see and, hopefully, give something back.

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This sounds like it might be a battery problem. These cars are sensitive to battery issues. If your battery has been drained by one of the many gremlins these cars can develop that could be it.

As to the alarm module, it's located up and above your right rear tail light area. It's a bit tricky to see sometimes and might be hard to unplug.

[m6bigdog]

Hi @JK840, I am looking for that trunk sensor in my 97 850CI.. I scoured these threads, procured shop manual PDFs, but didn't find the map to it. Do you have a link or pic by chance?

If anyone else sees this.. She sat in the Florida heat for a few weeks (a lady crunched my passenger door/front panel as I sat at a stoplight.. I am awaiting parts. Just bought her 2 months prior. Pretty devastated but she was getting years of love anyway, just had to reorder the list...) and after a couple of random flashing/alarm light episodes, she won't start. Starter could turn over a jet engine, but no fuel. Replaced fuel pump relay. Checked the other two relays in eBox, solid clicks. BaT seller listed a recent fuel pump rebuild, so I figured the pump will be last stop. This car had an odd journey I think - no alarm sound. The driver door will not lock, though the lock stem does move up/down. Almost like the car was .. neutralized. But I like puzzles..

I tried the method at top of thread (10 minutes in position 1), no dice.
Grateful for any guidance. This community is remarkable.. really fun to see and, hopefully, give something back.

My 97-850 had the rechargeable batteries go bad in the alarm siren (passenger side under the cowl).
symptoms:
The alarm would not chirp when armed/disarmed by the key remote and the alarm could go off shortly after the alarm was armed by the key remote.
Solution:
Replace the alarm siren.

[tvjake2]

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This sounds like it might be a battery problem. These cars are sensitive to battery issues. If your battery has been drained by one of the many gremlins these cars can develop that could be it.

As to the alarm module, it's located up and above your left rear tail light area. It's a bit tricky to see sometimes and might be hard to unplug.

Corrected post: alarm module is located above the LEFT side tail light assembly.

[Bengelbr]

Many thanks for the replies, much appreciated... I will be back to the car tomorrow and will see if I can figure this out.

[cartoonz]

Corrected post: alarm module is located above the LEFT side tail light assembly.

That isn't the alrm module, that is the tilt sensor.

[rjbaren]

I would like to be sure I am following correctly. If one were to disconnect the tilt sensor, then the alarm problems should be gone? No chirp, no alarm, and no alarm going off by itself?

[tvjake2]

That isn't the alrm module, that is the tilt sensor.

You are correct...my brain was on the fritz.

[bencrossman]

Where abouts is this fuse under the passenger side sill?

Thanks
Ben

[Bengelbr]

Thanks all for the responses - I can confirm that disconnecting the tilt sensor (clip-on cable connection) solved that no-ignition issue. I just left it disconnected. Such an interesting sensor assembly. Needed some smaller hands to get the cable connector off, for anyone else who needs to do this.

I waited a bit to respond because within a few days, had a new and different startup issue. This time, no starter turnover at all (prior issue had full starter revolutions, but no fuel/ignition.) If you like some detail: (***** long read*****)

Drove 10 miles on the freeway. Ran like a champ.
Parked on the street for dinner. *Nose pointed slightly downhill.* (The car sat inclined for many weeks in heat after recent collision, worth noting...)
Tried starting an hour later, no starter response. All other electrical behavior normal.

Son (13 yrs, he and I were out for his birthday dinner) helped me out. Confirmed fuel pump was producing an audible 'click' when I turned the key. Deduced that, symptomatically, this was not inclusive of prior startup issue I posted here. New problem clearly, but no evidence of trunk-tilt-sensor sponsored issue still present.
Immediate thought: gear position sensing. My 92 would occasionally behave this way, 20 years ago. I could easily rectify by jostling and resetting the shifter in park.
No luck with this vehicle. Noticed that gear selection displayed properly on the dash display as I shifted up and down. So, apparently not the sensor in the shifter assembly.
Recalled from watching Timm videos that the gear position sensor under the driver's side is fluid filled. Not a float sensor, but fluidic. I again found the post from Timm explaining that sensor, and figured I was screwed. Was now 10pm on a school night with my son, watching a video in our once-again-disabled project car.
Already had one fluidic, tilt-sensitive probe act up. Maybe this sensor was just.. congested, from cooking on the driveway on incline.
We got out, my son grabbed the driver side pillar, I went to the trunk, and on 3 we rocked the car on 2 axes, 3 or 4 times. Got in, started up, drove home.
She ran like a thoroughbred.

Hypothesis was that fluid dynamics in that gear selection sensor were compromised, and that affected conduction. Hoped in that moment it was transient, since only an hour before all was fine. I note again that with nose in declination, the "rock and roll" did the trick. Not the same as the trunk inclination sensor in function or form, but we correlated the declination angle with fluid behavior/influence on the sensor function.
Have had 2 more "no starter" episodes since. Both with the nose inclined when attempting start. Both resolved after the car (painfully) repositioned to no incline.

Bought a replacement sensor, not yet installed. My son is going to help. We will see if the hypothesis about this sensor is correct, or if there is another correlation that was not apparent.. like a loose electrical connection elsewhere, transient but receptive to inclination/jostling.

This was the plan in buying her, all along. A series of projects for us on a car that most folks would probably never dream of wrenching. He now knows that we can solve hard problems together. Dad wanted to drive the car home that night, because the car was not "broken down", so we made it happen... but only because a group of folks Dad never met had shared their knowledge for others' benefit. I told him he can be those guys someday.
We both reiterate our gratitude here.. thank you, birthday evening was very memorable.

The order of sub projects is not what I planned, but great life lesson for him there, too.

Thought I would share this Dickens novel of a post so new forum folk like me understand the power of the community here. Whether I have the cause nailed or not, knowing what was in play - and just believing we could find answers if we tried - motivated another 20 minutes of research, tinkering, and experimentation when it was almost certainly time for Uber home, and a tow.

Will post results. If I'm wrong, I'll have a gear position sensor for sale, used but functional

[rogbmw]

I once had an issue with the alarm on one of my 8s. The way we ultimately ended the problem was to disable the alarm by pulling the fuse on the alarm unit. It is located on the passenger side on the outside. Open the door, remove the plastic trim at the bottom of the door sill. Pull back the carpet and the control unit is located on the inside of the sill. Remove the fuse, and the alarm system is disabled.

[bdiefAZ]

Later model e31's need the Alarm siren batteries replaced, or a NEW siren installed.