Hamilton & Palmer Alarm Siren

[reds12]

Hi all,

I've had issues with my alarm randomly going off (1998 model 996), naturally this occurs at 2am, and makes me popular with the neighbours. I've had various bleeps out of the horn and followed the usual testing logic of doors being closed etc., but couldn't get the thing to stop, it would go off when unlocked and even when started. Have resolved for the meantime by temporarily disconnecting the siren! I don't think it battery (currently on the CTEK) or microswitch related but I could be wrong.

In tracing the possible fault, I have noticed the tilt sensor is sloshing with water so this likely needs replacing (although there is some info online suggesting these should have some sort of fluid in?). The issue I write about however, is linked to the alarm siren and the fact it looks like there have been repairs in the past, and also corrosion, and one of the backup battery negative cables not being connected.

I've contacted H&P this morning but thought I would post on here if anyone had encountered anything similar, and how/if they overcame the issue?

There are items on ebay but reluctant to buy with no evidence of them being tested and I note I can buy a replacement siren from Porsche (p/n 99661823701) but there are multiple revision numbers available so not sure which I would need.

Apologies for the long post but siren pictures attached for interest - is the brown silicon normal? It definitely doesn't look OE in there!

Thanks in advance for any guidance/advice.

 

[PeterHoward]

You wont get one from Porsche, NLA

 

[911UK]

Home

which alarm model is this,

 

[reds12]

Thank you, yes, I have just spoken to Exeter OPC who confirmed the most recent part, p/n 99661823705 has been discontinued (in 2020, apparently!). I emailed H&P using the email address on their homepage, as linked above.

It's the standard factory cat 1 alarm in my 1998 Carrera.

 

[PeterHoward]

Loads on ebay at about £30

 

[JasonH1969]

I've had a number of early 2000s era Mercedes over the past 5 or 6 years and a common fault is dying internal siren batteries at this sort of age; be careful if you buy a second hand siren as I know a few people who bought MB sirens only to find the batteries were dead or had leaked. This sets up a constant charging issue and causes parasitic battery drain on the car's main battery. I had this issue on two cars.

 

[reds12]

Thanks both - I was trying to avoid a second hand ebay unit for that very reason, but it may come to it!

I had a reply from H&P confirming they no longer make the siren unit so corroborates to what Porsche said. Waiting on a call back from the specialist I use, who did mention the siren failing was becoming quite common, so hoping they can offer an alternative solution. I will update this thread if I make any progress!

 

[wellsy]

I too had this issue some time ago and followed a similar path but I didn't get a reply from H&P. I'm afraid I don't have a solution to share as I simply disconnected the siren and stuck it on a shelf. If it's a battery issue a competent electrical person (not me!) could possibly replace?

 

[andrew97]

When I got my car someone had removed the siren previously, which i am not to worried about, however when the car is locked I get the annoying horn chirp to say all is not well with the alarm system, do you get that too?

 

[reds12]

Thanks for the replies.

Not heard from specialist yet but have been given an auto electrician contact, I agree it shouldn't be too hard for someone competent (also not me!) to fix. Worst case I guess an aftermarket alarm wouldn't be that complicated or expensive to fit...

I had various chirps from it when it went haywire, but couldn't seem to rationalise them. Really I need to plug it all back in and try and diagnose it more methodically but I probably need to find a deserted car park to do it in, as to avoid lynching from my neighbours! I'm not sure if the horn would chip if the alarm control unit knows the siren isn't plugged in. I did read that unplugging the tilt sensor and not coding it out would very likely result in the alarm continuing to go off.

Electrics eh!

 

[stuartb3502]

Hi,

In case you need to change the sounder battery. I changed mine a few years back. I managed to find a battery at this link:

http://www.xcelplus.co.uk/index.php/volvo5.html

Unfortunately, that site is currently down saying "new site coming soon". I did send them a picture of the connector on my alarm sounder and they supplied the battery with the correct connector. The battery is gummed inside the sounder, so it's a bit messy removing, but connects and fits easily and this solved the problem I was having at the time caused by the dead sounder backup battery.

There were two batteries in on this iosting available at the time, a 150 mAh and a 320 mAh. The 996 sounder has a 330 mAh battery, so get the bigger one.

Ping me if I can clarify further (I can probably find some pictures).

Cheers
Stuart

 

[reds12]

Thanks Stuart, that's super helpful info - much appreciated! I see they have an ebay page so I can drop them a message there.

I've not had the opportunity to do anything with the alarm yet but car is booked into specialist next week pre-MOT, so will have a chat to them about it then.

 

[NeunGruppen]

Hi,
I had this, exactly the same and I went through a fairly expensive process trying to diagnose the fault - You’re correct that the siren is unavailable and in my case the rechargeable battery inside the H&P unit was dead causing the siren to ‘let me know’ plus I couldn’t find a replacement either. The tilt sensor is the white fluid filled cube next to the sounder. In diagnosing my problem I had it replaced to the new version under the passenger seat by my OPC, and replaced the bonnet catch, and bought new keys trying to solve it.

After all that didn’t work I contacted the PCGB 996 register for more ideas. It seems that the H&P siren was an add-on for the insurers in the UK market, an addition to the Porsche alarm fitted to all 996 models. They suggested that I unplug it and see. I did and it hasn’t been an issue since. The Porsche alarm system uses the car horn and that still works…

It could be that the updated tilt sensor that I had installed is coded into the Porsche system, bypassing the H&P siren due to the part being obsolete but I have no way of know if this is the case…

 

[andrew97]

Thanks for this info, when I got my car the alarm siren and level sensor where not there, (just the plugs) and I couldn't understand how my alarm still seemed to be working, albeit with a horn chirp when locked. This makes sense now as the actual alarm is still there.

Does you alarm function as expected, with no chirp without the H&P unit unplugged?

 

[NeunGruppen]

Yes, totally fine. It’s the Porsche alarm system. The H&P unit was a UK add-on as far as I know!