Bloody Alarm!

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dazthephot
Joined: Wed 09 Apr, 2008 19:58
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Bloody Alarm!

Post by dazthephot » Fri 05 Jan, 2018 14:38

Ok I’m fed up with this now. This alarm is rubbish. If it’s not one thing it’s another.

So far the boot wells filling up with water have knackered two tilt sensors. I have taken it out as the wire harness has rotted away at the pins. I’ve punched holes in the bungs to stop the wells filling up too much.

I’ve checked the plunger switch behind the head unit, it’s cable tied in.
I’ve checked the bonnet plunger switch, seems ok but I may replace it anyway as it’s a cheap part.
I haven’t tested the boot lock plunger switch yet, could be the issue.
I haven’t tested the ultrasonic sensor as I don’t know how test that beyond removing it.
I haven’t done a continuity check on the boot lid wiring harness yet.
The door lockplate interior light switches seem ok as the interior light still works as normal.

This is my train of thought for fixing the alarm. Have I missed anything?

Can the alarm be removed?


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zedzedthree
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Re: Bloody Alarm!

Post by zedzedthree » Sat 06 Jan, 2018 01:21

If the radio switch is cable tied closed it can simply be removed (and kept somewhere safe) and the alarm will no longer look at it,the bonnet switch is wired in parallel with the bonnet switch thus a fault on either will trigger the alarm.
You can easily pull the plug from the bonnet switch to see if this is the point at which triggering happens,mine was replaced due to false alarms and I seem to remember the new one was the same as fitted to X5 vehicles.
My money would be a bonnet switch fault rather than interior alarm module.
If you wish,the alarm can be deleted but consider how this would impact on your insurance.

John Wilson
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Re: Bloody Alarm!

Post by John Wilson » Sat 06 Jan, 2018 14:26

Can’t you get to the bottom of the problem of why the boot is filling with water, rather than just making holes for its escape. It’s usually caused by the ariel grommet perishing which is a simple fix.

zedzedthree
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Re: Bloody Alarm!

Post by zedzedthree » Sat 06 Jan, 2018 15:19

Intended to say: bonnet switch is connected in parallel with radio switch.
Should be easy fix in any case,just be systematic.
The only false triggering of the internal microwave alarm has been as result of radio frequency transmission in near vicinity of vehicle,often FM modulated so this is last sensor to be thinking about,anyhow,you can isolate the module by unplugging.

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dazthephot
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Re: Bloody Alarm!

Post by dazthephot » Sat 06 Jan, 2018 16:07

Ok some progress.

I started at the bonnet switch. I pulled it out and tested for continuity. It works just fine. However when I hold it down and set the alarm, wait a few minutes then release it the alarm doesn’t sound. I’m now baffled by that bit.

Then I’m in the boot looking for the source of the water ingress and then boot light went out. So now I’m trying to see if the boot plunger is faulty. Tested again for continuity and all is well but I just happened to catch the boot wiring loom and the light flickered. I’ve been putting this off but now I have to look at the wiring. This is what I found. ImageImage

Clearly someone in the past has been digging around in here, not sealed the wiring back up and moisture has caused the copper to decay and eventually the wires have broken.

Could this have been the problem with the alarm all along?

I’ve soldered and join the wires together and taped up the exposed wires. I could do with a new sleeve solution as I had to destroy the original to get at the wiring.

The car is now alarmed and I’m waiting to see if it goes off. I haven’t touched the ultrasonic (not microwave) sensor yet.

The water ingress source is my next big job.


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dazthephot
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Re: Bloody Alarm!

Post by dazthephot » Sat 06 Jan, 2018 16:12

John Wilson wrote:Can’t you get to the bottom of the problem of why the boot is filling with water, rather than just making holes for its escape. It’s usually caused by the ariel grommet perishing which is a simple fix.
I’m ongoing with that John. The first thing I changed was the aerial grommet which had perished. I’ve checked underneath and around inside since then and it’s bone dry but the wells are still filling up.
My next step is the high level brake light seal as there’s a lot of moisture underneath the boot lid but that might be condensation from the damp boot liner.


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zedzedthree
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Re: Bloody Alarm!

Post by zedzedthree » Sat 06 Jan, 2018 20:35

That carnage is typical of the boot loom due to poor original design that attempts to fold the wire.When I repaired my boot loom I cut the damaged section out and remade it using waterproof multi-way automotive connectors and recased the wiring in corrugated flexi conduit.
This alone may account for false alarming but the bonnet switch is still highly suspect.
You refer to the ultrasonic alarm fitted to a year 2000 facelift 1.9,I presume this is an add on with transmitter and receiver transducers on pillars or visor area?
Factory spec alarm fit 1999 onward is 2.4gHZ microwave interior sensor on trim panel adjacent OBD2 port.

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Robert T
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Re: Bloody Alarm!

Post by Robert T » Sat 06 Jan, 2018 22:43

To my knowledge all UK Z3s from about 09/98 have the same alarm system with the buttons on the key. The interior movement sensor is ultrasonic, but mounted in the centre console. Microwave was only fitted as an upgrade to cars reporting problems with the ultrasonic units.

I have the later alarm on my 01/99 pre-facelift car and I had a problem with the alarm going off at random. Sometime later I found an EWS3G label in the driver's footwell. Methinks it had been wafting in the breeze and setting the alarm off, as the alarm is fine now.

To help diagnose the alarm problem, does the alarm still go off if you don't set it? Just lock the car with the key and not the remote. If it still goes off it is likely to still be an issue with the tilt sensor wiring, as this is the only thing I know off that seems to be able to trigger the alarm when it isn't set.

The bonnet switch might not be working if the stereo switch is in the closed position when the alarm is armed. The alarm will disregard any sensor not in the correct state when arming. Thus releasing the bonnet switch and closing the circuit has no effect.

The perimetric switches are all the same as for the lighting. One thing to watch for is wear in the buttons in the door latches. The tell tale sign is that the interior light comes on randomly when the doors are closed. Make sure it isn't in the off position first. Similarly, the boot light switch in the boot lock detects the boot opening. The wiring for this goes through the loom of doom in the boot.

Finally, try setting the alarm with the interior movement sensor disabled. To do this, lock the car with the remote and then press the lock button a second time within a second or so. If it still goes off, it's not the movement sensors. You can check them by leaving the window down and reaching down to put you hand on the seat base. The should normally trigger the alarm before your hand reaches the seat. With them disabled you should be able to touch the seat.

Cheers R.

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zedzedthree
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Re: Bloody Alarm!

Post by zedzedthree » Sat 06 Jan, 2018 23:16

Thanks for the useful extra alarm information.
Seems like my car only ever had the microwave alarm module from new ( known car from original day of sale) no blank etc where ultrasonic may have been deleted from my console-my experience has always been that these systems rely on a certain spacing between transmit and receive transducers,maybe BMW just went over to microwave alarm due to said problem?
Will look at build sheet and see what BMW reckon was fitted when built.

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dazthephot
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Re: Bloody Alarm!

Post by dazthephot » Sun 07 Jan, 2018 18:00

Great info.

That explains the bonnet switch as I know the stereo one is cable tied closed.
I had to pull the tilt sensor out as it was constantly flooded.
Since repairing the boot wiring loom the car has been alarmed and hasn’t gone off for 36 hours now. My theory is that moisture and/or movement has led to a voltage drop of the bootlight (this was one of the broken decayed wires) and set off the alarm.

My 99 1.9 is the wide bodied one and I’ve seen the white ultrasonic sensor box because i noticed it the last time I had the lower panel down. I will have a look again to confirm whether it’s the ultrasonic or microwave and report.

I don’t have any issues with the interior light and the door switches are fine too as I needed to test them when sorting the lock actuator issues. ( see my other issue on Chinese copies lol).

Anyway fingers crossed I’ve sorted the alarm. My next job is the water ingress. I’m leaning towards the centre brake light so I’m going to tape some clear plastic underneath it and seal it so I can check it.
I will report back.



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