Alarm System Fault

MikeP

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British Zeds
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Jul 1, 2025
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13
Location
West Sussex
Model of Z
Z3
Hi All,
I have recently purchased a 2000 (W Reg) 1.9 Z3 Roadster and am having some issues with the alarm system.
The owner's handbook that came with the car refers to movement sensors in the driver's and passenger's foot-wells allowing the alarm to be used with the hood down.
There is a small red indicator for the alarm system in the rear console between the hood opening button and the heated rear window button.
When I set the alarm with the key fob the red indicator flashes rapidly for approximately 10 seconds and then flashes at approximately once per second.
If I put my arm down into the passenger foot-well it appears to trigger the alarm and all of the indicators flash but there is no horn/klaxon.
If I put my arm down into the driver's foot-well the alarm doesn't trigger at all.
Can anyone advise -
Where are the foot-well movement sensors are located (any photos of what I am looking for would be appreciated)?
How to get the horn/klaxon to sound when the alarm is triggered?
Looking on various forums I see a lot of comments regarding the module in the nearside rear wing faulting due to water ingress - I have checked and this area is dry with no evidence of any previous ingress.
Any help would be much appreciated !
 

Tony Francis

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British Zeds
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Location
South Somerset
Model of Z
Z3 1.8 M43TU
So you have a facelift car with the alarm integrated to the central locking? pre facelift cars had a separate alarm fob and the alarm sounder under the bonnet could be switched off with a key so that just the indicators flashed if the alarm was triggered. If you have a pre facelift car then I would think that the alarm sounder was turned off. However facelift cars had a factory fit alarm and the alarm sounder cannot be switched off, if the alarm is triggered then the indicators flash and you will hear a loud “beep, beep beep”. Where in the hand book have you seen the reference to the sensors in the footwells? I have a 1999 facelift car and I can’t recall reading that specifically in the handbook. There are interior sensors and if you press the locking button twice you lock the car and set the alarm but without the interior sensors on according to my handbook.
 

Tony Francis

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Thinkin about this a bit more Mike, my reading of the handbook is that if you get a rapid flashing of the alarm indicator when you lock the car then it is telling you that part of the system has not armed due to a fault, it then changes to the slow steady flash to show that the rest of the system is armed. Unfortunately I have not been able to find out how you tell which part of the system is affected, maybe for your car it is one of the interior sensors? I am still puzzled by the fact that you don’t get an audible alarm.
 

NZ00Z3

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my reading of the handbook is that if you get a rapid flashing of the alarm indicator when you lock the car then it is telling you that part of the system has not armed due to a fault, it then changes to the slow steady flash to show that the rest of the system is armed.
This is correct. Your alarm system is armed but one of the triggers is not set. This can be sorted with INPA as it will show you the activation of all of the triggers.

The common ones to give problems are:
- Tilt sensor in the left back wing. You've already checked this one.
- Bonnet/hood sensor. Left side at the front of the engine bay. Unplug it to disable it and see if the alarm fully arms
- Radio Theft sensor at the back of the radio. Especially if you have an aftermarket radio. Unplug it to disable it and see if the alarm fully arms.
- Door switches. These are a little square push switch in the back of the door striker pin (on the car not the door). Put a couple of layers of tape on the square to build id up and see if the alarm fully arms. You can also push your knee on the door as you lock the car to take out any slack.
 

MikeP

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British Zeds
Joined
Jul 1, 2025
Points
13
Location
West Sussex
Model of Z
Z3
Thank you both for your replies.
Tony - see attached pages from my manual referring to the movement sensors.
As I see it I have two problems ........

Firstly, when the alarm does trigger only the indicators flash, there is no klaxon/horn.

Secondly one or more of the sensors are not working -
I will check the bonnet and radio today, the door switches are turning on the interior light OK so I think these must be working
The movement detector for the drivers foot-well is definitely not working but I can't physically find it! - any pointers would be appreciated

I have seen various comments about INPA - is this available to DIY users or do I need to go to a dealer to get this done?

Thanks again !
 

Attachments

MikeP

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British Zeds
Joined
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Points
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Location
West Sussex
Model of Z
Z3
Hi Again,
Just an update on my post earlier today .......

I found a copy of the year 2000 electrical trouble shooting manual (thanks Zorg Guru (IV)) and have checked fuses 2, 7, 16, 31 and 34 and all are OK

I have checked the bonnet switch with a multi-meter and the contacts are definitely changing over (I have left it unplugged for now).

I have checked the boot switch and the boot light definitely goes out when the boot lid is closed.

The car is fitted with an aftermarket radio
I took the radio out and couldn't see any switch however there is a mounting block behind the radio which used to engage on a pin protruding from the back of the original radio - is this the switch?
If so any suggestions how I disable it?


IMG_20250710_122211.jpg
IMG_20250710_155137.jpg
 

Tony Francis

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Z3 1.8 M43TU
Thank you both for your replies.
Tony - see attached pages from my manual referring to the movement sensors.
Your manual is slightly different to mine, I don’t have that paragraph or diagram. Useful to know though!
 

NZ00Z3

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INPA is a user software that runs on a window computer/tablet. I can be down loaded here: https://www.bimmerforums.com/forum/...tions-Experiences-Discussions-Experimentation

The movement detector in a 2000 Z3 that I owned was under the center console in front of the gear lever.

Yes that square box is the radio alarm switch. See the zip tie, it is holding the switch in the correct position. So, it not the problem.
 

MikeP

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British Zeds
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Location
West Sussex
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Z3
Thanks for your feedback -
It looks like it may be just the driver's foot-well sensor that is causing the issue.
Any thoughts as to why the horn/klaxon is not sounding when the alarm does trigger?

Any pointers as to where I can buy the INPA interface cable ?
 

NZ00Z3

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New Zealand Zeds
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I put "INPA Cable" into eBay UK and got several hits for the right product.
 

MikeP

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British Zeds
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Points
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Location
West Sussex
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Z3
Hi,
Any thoughts on why the klaxon doesn't sound when the alarm triggers?
Can I test it on the bench?
Looking at the wiring diagram it has a permanent live feed via terminal 3 and a ground connection via terminal 1 but terminals 2 & 4 connect to the ZKE control unit.
 

MikeP

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British Zeds
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Points
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Location
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I seem to be going backwards here ! ..........
When I first posted this thread the situation was :

"When I set the alarm with the key fob the red indicator flashes rapidly for approximately 10 seconds and then flashes at approximately once per second.
If I put my arm down into the passenger foot-well it appears to trigger the alarm and all of the indicators flash but there is no horn/klaxon.
If I put my arm down into the driver's foot-well the alarm doesn't trigger at all. "


I tested the door and boot switches by opening with the key and they were OK and I disconnected the bonnet switch to eliminate this.
I concluded that the drivers side movement detector must have failed so looked into sourcing a replacement.
I found the sensor on the inside of the trim section above the driver's knees and this had a part number 65756906104 (see photo)
My local BMW garage said this had been superseded (multiple times) and the final replacement part number was 65756974631.
I sourced one of these on eBay (see photo) and although the mounting arrangement was completely different the electrical connection was the same so I went ahead and fitted it.
When I tried to set the alarm I got the same rapid flashing from the indicator in the rear console and now neither the passenger or the replacement movement sensors are working !

I understand that the alarm components on the 2000 Z3 were not "coded" so replacing a component like this shouldn't be an issue

Can anyone suggest how to move forward?

At Zorg Guru's suggestion I am looking at getting an old laptop and cable for INPA but when I look on eBay UK I can only see cables to connect to the port in the driver's foot-well which I understand will only give engine diagnostic information so I need a cable with the (20 pin?) round plug - again any pointers would be much appreciated.

Original Driver's Side Movement Detector :

IMG_20250716_144748 Cropped.jpg


Replacement Driver's Side Movement Detector :

IMG_20250721_202156 Cropped.jpg
 

NZ00Z3

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Yes you will need the 20 pin round connector.

You don't need a windows XP computer to connect to your car. Any window 10 computer will do.
 

MikeP

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British Zeds
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Thanks Zorg Guru,
Any thoughts why plugging in the replacement driver's side movement detector killed of the passenger's side?
 

NZ00Z3

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New Zealand Zeds
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Location
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They both look good

The purpose of the switch in the main cable is to short terminals 7 & 8 in the OBD connector. This is required in the Z3's so that you can read all modules.
 

MikeP

Regular Member
British Zeds
Joined
Jul 1, 2025
Points
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Location
West Sussex
Model of Z
Z3
Hi again,
I have tried installing the INPA software and have had some issues which I thought would be better posted as a new thread
Any feedback would be appreciated :)
 
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