944 S2 Alarm problem - fixed

[Monkeythree]

The mystery box by the battery is an extension module from the standard alarm system which runs the ultrasonic movement detectors fitted in the rear pillars.

 

[squall457]

Thanks for that info Monkeythree... I've disconnected the wires to the sensors now... fingers crossed this does the trick!!

 

[squall457]

Hey,

I recently bought a 1991 944 S2 and have been loving it, apart from the fact that it has an alarm issue that I did not know about when buying the car.

Basically, when locked, the standard alarm will go off randomly.. never just straight away, sometimes after many hours.

A previous owner has installed an aftermarket Cobra alarm system (in 2004 by a Cobra authorised dealer) which is working perfectly (I've tested it, and it uses a different siren to the standard one)

The car had a standard immboliser fitted which I presume has been by-bassed, since the car always starts fine and there is nowhere to put the chip (I think it went to the left of the switches, and has been replaced with a blank switch).
The standard alarm light near the switches (to the right) is constantly flashing, regardless of door lock status or if the engine is running. The thing on the opposite side is the light/button for the Cobra alarm which is working as it should.

All power lock functions work as they should, including the lights flashing in the door pins when locked. The battery is tested to be perfect and the alarm never comes on if doors are unlocked.

I found something by the battery that I can't make out what it is (pictures attached).. does anybody know if it's to do with the standard alarm? I found the cobra control unit in the passenger footwell while trying to find the standard one based on what I read from Clark's guide.. couldn't see the standard one.

This is driving me mental and is really ruining the car for me, does anyone have any ideas on what the problem could be or what to try? Thanks!

Mystery box behind battery:

 

[squall457]

The alarm still went off Moving back more of the carpet in the boot by the box handily revealed a connector, just when I was ready with wire cutters... so I've now just disconnected and removed the whole box. Let's see how it goes

 

[Monkeythree]

I was just identifying the box. it might not be related to your alarm woes. You said there are now two alarms, the standard Porsche one and the Cobra one. Are you sure you know which one is playing up? TBH, if one is working fine then I'd be tempted just to pull the fuse from the one that is not working properly and run with one. BTW, The alarm module on the late S2's rides piggyback on the ECU under the panel in the passenger footwell. It might be a bit crowded with wiring down there if you've got a Cobra module in the mix too but a few minutes spent studying which wire goes where and you will soon figure out what does what.

 

[squall457]

Yeh it's definitwy the standard one playing up, the Cobra one uses a different siren and its working perfectly. Don't want to speak too soon but the alarm hasn't gone off so far so Im hoping removing that sensor control unit has sorted it, but if not do you know the easiest way to disable the standard alarm? Seems very strange that someone would go through the trouble of removing he standard immobiliser, installing after market alarm but leaving the standard alarm.. In the passenger footwell, I found the cobra unit behind a big black plastic cover that looks to have more wiring behind it.. Is this where the standard one would be? Is the plastic covering removable do you know?

 

[Monkeythree]

AFAIK, there was no standard (by this I assume you mean factory fitted) immobiliser on S2's. The late ones had a factory fitted alarm but, I believe, no immobiliser. So I'm not sure what you think has been removed?? To get to the factory alarm module, you first have to remove the plywood panel in the footwell. That will reveal a pressed steel cradle which holds the ECU. Unbolt the steel cradle and look underneath the ECU and you should find the factory alarm module riding piggyback on the ECU. As far as disabling it goes, I'm pretty sure there is a fuse for it in the fusebox so I would try just pulling the fuse. Or I suppose you could just unplug the whole module from the wiring loom.

 

[squall457]

Thought I'd give a little update on this a week on.. alarm has not gone off all week, so it must have been a dodgy sensor control unit and removing it has fixed it! The installed aftermarket alarm has its own control unit and separate interior sensors that are working correctly, so sorted In regards to the disabled standard immobiliser.. there are stickers on the door,and I got the immobiliser chips with the keys, plus now have I found the port for them near the ignition key. I've never needed to use these, so must have been bypassed at some point but no idea how :

(Please excuse the wear on the black part running along the side of the window.. does anybody know if this is replaceable?)

Now that I've found the port for the immobiliser chip, it's left me confused as to what my left-most switch on the centre console is for.. Anybody got any ideas?

 

[Waylander]

The door pillar is not a part you can replace, as I am crap with a rattle can, I bought a metre of matt black vinyl wrap of the bay and took some time and wrapped them, easy to do and the finish is great took about 45 mins a side. Looks like your car has had more than one alarm fitted, the slot by the ignition key is the dealer fitted Hamilton Palmer immobiliser when the car was new,

 

[944Scott]

Like what waylander said. I rubbed mine back and covered it in 2in electrical tape, its been there two years and looks fine []

 

[Mike_Pollock]

Your switch probably does nothing - most uk cars have a blanking plate, but my S2 has a spare switch

 

[Waylander]

door pillars

Finished

 

[zcacogp]

Ben, The switch would have been to turn the interior sensors on the standard alarm on and off, allowing you to set the alarm with the windows or sunroof open without it triggering in the wind. Martin, that's a very tidy job with the wrap you have done. How did you tuck it behind the trims at the top and bottom? Or did you remove them to fit the wrap? Oli.

 

[Waylander]

took them off, so much easier. and I had a bag full of new clips so it just made sense to do it at the same time

 

[squall457]

Cheers for the info everyone Great tips on the vinyl trim, definitely going to give that a go soon.. so unnecessary to try and completley remove the current one first?

 

[944Fripp]

Just coming back to the original post I didn't see this the first time round so I might have been able to help a bit sooner...i read the original post and thought about that little box in the back straight away! I had a problem a couple of years ago when the alarm kept going off. I took it to a specialist who claimed to know about 944's (I was away from home at the time), turns out the guy knew everything there was to know about 944's (based up in Sterling...like some weird mystical 944 guru I now can't find any info about him!) and asked me to describe exactly what happened when the alarm went off. The telling sign was that the interior light flashed too and with that info he went straight to the boot and pulled the box out. Yep, it is the controller for the ultrasonic interior alarm and it was full of water! Shortly after that I replaced the boot seal and left the box out. My guess is that disconnecting the sensors may not have worked but I can vouch for taking the whole thing out working a treat! []