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E 30 325iS Battery Replacement Car Starts/Alarm Will Not Shut Off

Discussion in 'Audio, Video & Electronics' started by 182803, Apr 3, 2017.

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    182803

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    When I try to install a new battery the car starts and drives but the alarm will not shut off. I have read various posts across forums net wide and the problem is typically the car will not start while the alarm blares and have yet to find one addressing this issue.

    There may be other electrical issues: For example something is draining the battery when the car is off and there are good posts to troubleshoot that, an issue which clearly needs solving. But to do the testing it would be nice to have a battery in place without all the racket. Can anyone tell me how to disconnect the alarm so I can get to that point?

    I purchased this car 3 years ago so I do not know if the alarm is OEM or aftermarket. Nor do I know the "code" - do I take my title over to a BMW dealer to obtain it? Any assistance is much appreciated.
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    charlson89

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    The link below shows the location of the OEM alarm module. The first step is to identify if you have a OEM alarm or aftermarket this will help with diagnosis with how to disable it. If it is OEM just unplug the module and see if the vehicle still starts. If the alarm is going off and the vehicle starts this makes me think the alarm is not working properly since it should not allow the vehicle to start.
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    MGarrison

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    Is it sounding the car's stock horns or is there an aftermarket alarm horn? An aftermarket alarm horn, you could unplug it or cut one of the wires going to it - if it's the car's stock horns, then maybe start by unplugging the OBC, which you might be able to get to the back of if you can pull the radio. More stuff to remove from the the glovebox side (nix the OBC; yes, if stock alarm, find alarm module, unplug that). Start at the beginning of realoem.com and put in the last 7 of your VIN or just get to the right yr/month production for your car from the "classic" section - here's a diagram, '91 325i sedan -

    http://www.realoem.com/bmw/enUS/showparts?id=1413-USA-01-1991-E30-BMW-325i&diagId=62_0069

    You could unplug the car horns, although you probably have to remove some trim panels, etc. to gain access to those - plugs could be fragile too, might crumble trying to pull them apart, but, it would disable the horns - obviously then, no horns for driving either. Unplugging OBC, not sure, but you'd probably still have horn buttons working. The above diagram shows the horn part number, but not where the horns are installed. I think they're typically in the space between the wheels & front bumper, 1 on each side (adding - don't know where the alarm module is isntalled - realoem might show it, Charlson can relay correct link).

    I don't know about later OBC's, but earlier ones, disconnecting the battery also clears out any OBC code. That function of an OBC, when you push the code button, (I think key has to be in the ignition, & turned at least to the accessory position), you input your own 4-digit code using the keypad. When you re-insert the key & turn it to accessory position, you have to input the code you entered before & it allows the car to start. As far as OBC, it's a user-generated code. The stock radios had a specific code to input in case of loss of power, but I don't think those were typically tied into an alarm system..... might be something with the door lock cyl. position/sensor? I'm wondering if it might be thinking the car door wasn't unlocked... The door lock cylinders wear, and at a certain point, the first lock detente won't lock/unlock, and turning further, the doors will lock/unlock, but you also engage the door deadbolt - at that point, it's a reallllllllly good idea to replace the door lock cylinder because the next lock cyl. failure mode is the deadbolt is engaged, and can't be unlocked - potentially leaving you locked out & with no way to open the door. There are E30 owners who get in the habit of locking/unlocking the car using the trunk lock to avoid such a scenario & the interminable lock cylinder wear. Eh, just a thought - ditto Charlson's line of thought, faulty alarm module would seem like 1st most-likely culprit.
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    182803

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    You help is much appreciated. I clicked the link and it appears the car may have a factory alarm.
    https://www.realoem.com/bmw/enUS/showparts?id=1113-USA-11-1988-E30-BMW-325i&diagId=62_0069
    But this is not my day job and it has been over 25 years since I truly worked on cars - restored a '67 TR4a - and they were much simpler machines.

    I'm virtually certain the noise is the OEM car horns. (The car is stored in a neighbor's garage for the winter and when getting it out this problem began. It was all I could do to get the car into my garage and shut the damn thing off.) So given the favorable weather this weekend I am going to try and tackle this by unplugging/disabling the horns - at least until I can figure our the root of the problem.

    This is my second 325iS, the first being a '90 I bought new and 10 years in Chicago essentially rusted out. Found this one 3 years ago - only in California and Arizona - and with 90,000 miles was in amazing shape. But I am a stickler for maintenance in that I want everything to function - even the non-essential items at all times in an effort to keep the car "as new" and completely stock. That being said, I will look into the door locks - I hardly ever lock the car but who knows what can happen/erode after 90,000 miles and 28 years.

    I also think I will try to reprogram the code for one try before I disable the horns because, tell me if I am nuts, if I reprogram it the alarm might actually cease? Probably wishful thinking on my part.

    Anyhow, many thanks for your suggestions. I am keeping my fingers crossed
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    MGarrison

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    Fuse #7 (15 amp - light blue) is the for the horns. Pulling that is an easy way to check if your stock horns are sounding. Here's some fusebox info, shows the location of the horn relay. The factory fusebox cover typically has the relay numbers printed on them to show which is which - if yours are like mine, they're orange, and there are a few identical orange ones.

    http://www.e30zone.net/e30zonewiki/index.php/Fuse_Box

    You can swap in an identical relay to test it (make sure they're the same).

    Read the factory alarm system sections here: pgs. 65-750 thru 754

    https://www.bmwtechinfo.com/repair/main/561en/htm/1233.htm

    It shows that if you have a (relatively early) factory alarm system, it looks like its control brain should be under the driver's side dash, you have to drop the trim panel under the steering column (easy to do). The upper front pieces have a single slot (they look like a black plastic round screwhead), turn 90 degrees and pull out to remove, the one in the center column is larger, I think that's also a 90 degree turn and pull out, but it's longer. Don't let the trim panel hang down unsupported, it's little more than a dense fiber/cardboard material - there's a support clip that holds up the end above the pedals, if you just let it drop down, the section in the clip can crack off, and then you don't have an easy way to keep it from drooping down and getting in the way of your feet (obviously problematic).

    If you have a factory alarm, as shown in the link above, there's a number of thing that could be causing an alarm malfunction and sounding the alarm horn, as indicated by the various locations it has sending a signal to the alarm brain box. Disconnecting the alarm control unit should shut up the alarm system, & since it has a section on installing/removing an alarm horn, a factory alarm apparently wouldn't seem to use the stock horns, so you'd be ok there disabling the alarm and keeping stock horns functioning (at least, in theory, and, assuming you do have a factory alarm!)

    I don't know if E30's are as subject to wonky electrical behavior from a low battery, but one thing to try would be double-checking if the battery's fully charged, and maybe disconnecting/reconnecting one of the battery cables to try a reset. If you do have a factory alarm, considering the worn-door-lock issue, make sure you turned the driver's door lock all the way to the open position. However, it would appear if the alarm is doing what it's supposed to, you shouldn't be able to start the car. However, old German circuit boards like the SI board can have bad/cracked solder connections from old age, I could see the same for an alarm brain box being possible.

    Here, someone was apparently selling a factory E30 alarm, looks like he relayed some verbiage on how it works, although what he says there is it uses the horns the car has.

    http://www.r3vlimited.com/board/showthread.php?t=132159

    Here's a thread on factory alarm system (radio key-fob remote) that appears to have been available towards the tail-end of the E30 run, interesting for curiosity's sake if nothing else -

    http://www.r3vlimited.com/board/showthread.php?t=196011

    If you have a non-stock alarm system and it's a non-stock horn that's sounding, then sound-wise you should be able to trace to the sound source.

    This thread has the stock horns wiring diagram - looks like normally there's nothing else that triggers the horns besides the steering wheel horn buttons -

    http://www.unofficialbmw.com/phpBB/viewtopic.php?t=33897&sid=f378f7787dd6e38a34db3d67f740350b

    Here's what the factory horns look like:

    https://www.realoem.com/bmw/enUS/showparts?id=1113-USA-11-1988-E30-BMW-325i&diagId=61_0959

    Wish this was a larger pic, but - gives you an idea what the components of the non-keyless alarm system look like.

    http://www.2040-parts.com/_content/items/images/17/2083017/001.jpg

    You can find an electrical troubleshooting manual (ETM) here:

    http://wedophones.com/BMWManualsLead.htm

    You might find more with more googling, but there's a few things!
    182803 likes this.
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    182803

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    Again - want you to know how much I appreciate all this help and information. Have allotted tomorrow afternoon and Sunday to work on and get the car ready for the summer. Looking forward to it.

    Will post a follow up with results.
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    182803

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    Pulling the horn fuse did not work. Turns out the car had an after market alarm, the guts of which were under the driver side dash. Unplugged the "brain" - the alarm box and all is normal again. Thanks.
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    charlson89

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    Great to hear you got that solved and out of the way.

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