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Discussion Starter · #1 ·
Having owned my Alfa for over a year now (97 1.8 16v)I have recently been having problems with the alarm. When I arm it after a few minutes or so it sets itself off, I,ve checked connections, terminals etc etc and even had it to an Alfa main dealers who informed me they never had the equipment to check it (tut!). Has anyone had the same problem or could give me some advice, I've got it switched off at the moment as not to disturb the neighbours but not something I want to leave off. You know what it's like!

Discussion Starter · #2 ·
I remember from a while back that there was a testing procedure for the alarms posted. I have found it again...

Start Quote>>>

Hi everyone,the alarm codes are:
Upon activating the alarm,the LED flashes to as follows:

8Hz 2.5s Door/bonnet/boot left open
On 2.5s Faulty ultrasonic sensors
16Hz 2.5s Control unit fault
Off LED fault

(i'm not sure about that we bit above - jason77)
(this bit below is very helpfull, it'll track down what's causing the alarm to set off - jason77)

Upon deactivation:

1 flash RH front door
2 flashes LH front door
3 flashes RH rear door
4 flashes LH rear door
5 flashes Ultrasonic sensors
6 flashes Bonnet
7 flashes Boot
8 flashes Key operated supply cut off
9 flashes Battery supply cut off
10 flashes 3 or more simultaneous alarms

You can also do a manual diagnosis as follows:

Open the bonnet and turn the ignition key from Marcia to Stop.

Within 15 seconds press the bonnet pin switch 7 times in less than 10 seconds.

You will hear 5 beeps and after 10 seconds the indicators will flash once.

The ultrasonics are now tested, if OK the indicators will flash 3 times and you will hear 3 beeps.

Now you can trigger each sensor in turn (doors/boot/bonnet)and if Ok each trigger will give a beep and a flash.

Turn the key to Marcia and you get a brief siren and the indicators will flash for 2.5 seconds. This operation will automatically exit the test mode, but you can also exit at any point by not triggering any sensor for 30 seconds, at which point the indicators will turn on for 2.5 seconds and a beep will sound.

End Quote>>>

You can then do some diagnostics on what's possibly faulty.

For more alarm info, do a search on 'alarm'. it'll find this quote and a load of other stuff.

good luck!

Discussion Starter · #3 ·
Thanks Jason, I'll be trying it out at the weekend hopefully after reading the text again to take it in. :confused:

Discussion Starter · #4 ·
Having searched the site there are usefull tips to try out, the only thing i'm not sure of is when people talk about the number of flashes. Is this the LED near to the key position, if so when the alarm goes off do you have to look at this for the number of flashes when you deactivate the alarm or am i missing something?


:) :)

Discussion Starter · #5 ·

It's the LED beside the ignition on the right. When you deactivate the alarm system look at the LED as you do it. If the alarm's been set off it'll start flashing like buggery. That will tell you which switch trioggered the alarm... just to test the sensors/switched run through the manual alarm test (turn key, bonnet switch loads of times etc.)

1,134 Posts
I've had a couple of minor problems with mine going off for no reason - I eventually put it down to the following conditions...

I had a few false alarms in the winter, I think due to temperature changes inside the car (cold air rushing in as I got out of a hot car, etc)

Like an idiot, I left my sunroof open in the rain once - followed later by false alarms. Dampness causing similar results to above.

Not long after I bought the car, it was always sounding the alarm. A few days later, I recovered a spider from around the ultrasonic sensors... problem solved!

Hope this may be of help.


Discussion Starter · #7 ·
After checking the individual sensors on the car as described there seems to be nothing wrong with them.
I can only put it down to the actual batteries in the alarm itself, what some people have had trouble with in the past. The problem is when I remove the plastic surround from the nearside wheel arch to get at the alarm there doesn't seem to be an easy way to remove the alarm itself.

Will the wires attached to the alarm move with it as to free it from its position?
Has anyone replaced the batteries who can give me some advice?


Discussion Starter · #9 ·
I remember Mike Scarf mentioning in a post that he had replaced the rechargeable batteries. I've looked up the post but it doesn't mention how he did it. I suggest e-mailing him and asking.

Do a search on all his posts via the memberlist (I think it's called "alarm again").


Discussion Starter · #10 ·
I see my name has been mentioned with the alarm.
Yes I did replace the rechargeable batteries.
I was getting 9 flashes on the fault code.
As I remember the alarm is held onto a bracket with a couple of nuts that were quite easy to get at with a 1/4" drive socket set or rachett spanner. The nuts were about 10mm. There is plenty of slack in the wiring as it runs from the front to the back of the wing.
I bought my batteries from from Tandy, I think I got the lot for £4 as they were on offer at the time.
The alarm itself comes apart easily, the only problem was the new battery cells were slightly thicker than the originals so I had to dispense with the original rubber battery holder as it became too fat to fit back inside the alarm. It took 5 minutes with a soldering iron to make up the new battery pack,using the original wires and connector soldered to the new cells.
I later had more alarm troubles (9flashes )which turned out to be a damaged earth cable behind the glovebox. Its been fine for the last few months since I did that.

Hope I have been of some use


Discussion Starter · #13 ·
The dredded alarm problem strikes again.
This time upon deactivation it gives 5 flashes which means something to do with the ultrasonics.

Can anyone tell me where the ultrasonics are placed in the inside of the car?
There is a small black box above the seat belt height adjusters, are these the ultrasonics?

What is the best way to check them?

Regards :eek:

Discussion Starter · #15 ·
Yeah, they are them. Pull off the little grilles to make sure the wires are in place..when I first got my car someone had disconnected them. Replace the grilles, lock yourself inside the car using the alarm fob, keep dead still while the alarm sets itself and then move! The alarm should obviously go off, having been activated by the sensors. I guess if you wanted to check one sensor at a time you could alternately disconnect the wires and then do the above. ;)

Discussion Starter · #16 ·
Hi Clive,

I don't suppose you know anything about the alarm system on the 164. It hasn't worked since I had it and have had a seperate Toad immobiliser fitted leaving the alarm system as a non working seperate system.

The chap I bought it from told me the dealer tried a new base unit and recode but to no avail :mad:

So other than taking it to my local dealer and being charged more than a replacement would be just for the diagnostic con I'm stuck as I'd like to get it working if possible bloody factory alarms total pants!

Any ideas anyone????????


164 Super


Discussion Starter · #17 ·
Sorry Mak, don't know about the 164. In what way doesn't it work. Is it just completely non-functioning or does it go off all the time or something? When I 1st got my 155 the alarm was troublesome but because it was under warranty I had the Base Unit changed by a Main Dealer (about £300 I think). It's been OK since. Apparently where it's sited it gets covered in water and when my old one came off it was full of the wet stuff! Getting back to yours, If it's totally dead and the previous owner insists that a new Base Unit was fitted, it might be a coding thing. If it's something else like going off spontaneously then I guess you'll have to go through the various sensors one by one using the old elimination thing. Good luck. ;)

Discussion Starter · #18 ·
Its just totally dead other than the little flashing bar on the dash/dial area which is on all the time.

I suppose it may be worth trying the code reset at the main dealer etc I'll give them a call but first get a chair :D


164 Super


Discussion Starter · #19 ·
Ian, if you do the sitting-in-car ultrasonic test then don't forget to don some ear protection!!! Rob155 - the caring face of Alfistiship!

Discussion Starter · #20 ·
I know this topic is going on a bit now but it's good I think for other people who may experience the problem in the future.

Anyway back to the question,

Does anybody know how to adjust the sensitivity of the ultrasonic sensors?
If so how do you do it?

It seems that mine are a little too sensitive,when a lorry etc passes close to the car it sets it off and the flashing LED tells me it's the sensors.

Regards :D
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