OliverK5

Hi all,

I’ve been searching the internet trying to find info on Sigma alarms and dealers but no luck – are they still manufactured? The only site that comes up is this one.
Basically I don’t have a Scooby (at the moment!) the sigma alarm if fitted to another car that I have recently bought – not sure on the model of Sigma – is there any way I can tell (would say the alarm is 10 or more years old) the only units I can find are AC-29 and AC-10 ? also two ultrasonic sensors
The problem is the alarm is fine until late afternoon when the sun starts to shine on the car, then it goes off, when the car is hot inside (with this great weather) the alarm goes off straight away after setting!
I’ve been told I need to see a Sigma dealer but no one knows where to find one? (south / west Yorkshire)

Can any of you guys shed any light on the above, your help is very much appreciated

MR_TOAD_INSTALLER

iTrader: (1)

Hi mate
Give me a ring 07774 446402 west yorkshire
Should be able to help you

Regards Ian

OliverK5

Thanks for the reply, found the cpu under the dash, its marked sg20e if that means anything?

wannaB4

Probably the ultra sonics picking up the air movement as the air in the car heats up.

OliverK5

I tried covering up the ultrasonic’s with black tape (not sure if this would stop the beam) but it still went off. When the car is cool its fine!

Sigma Sam

As posted, it sounds to me that the sensitivity of the ultrasonics is set too high. I doubt the tape will make a great deal of difference as the ultrasound will pass though this relatively unhindered.
It's also possible that the ultrasonic heads themselves may need repacing as they deteriate over time and I suspect this system is around 10years old now.

Unfortunately the ultrasonic sensitivity on this system can only be adjusted by a Sigma dealer using a programmer. They will also be able to check that the ultrasonics were infact the cause of the trigger using the programmer.
If the adjustment doesn't cure the problem then are new pair of heads may be needed. The part number for these is AC20S.

If you have trouble finding a Sigma dealer in the yellow pages etc, you can contact our sales desk on 0870 417 7795 who should be able to advise you of your nearest dealer. Just check that it is a Sigma dealer as Toad dealers are also listed on the database, but will not have the necessay programmer.

SS

OliverK5

Thanks for your reply Sigma Sam

OliverK5

I was unable to find any sigma dealers to look at the problem so I bought a new set of heads but still experience the same problem.

One thing I have noticed is that when the car is in the garage and the system is armed, the L.E.D blinks solid every second (or so) – alarm does not trigger
If the car is outside and there is excessive light on the car from the sun, when arming the led blinks quicker and is also dimmer (not from the sun shining on it) sometimes it will then go to blinking more solid every second or it will continue blinking fast until the interior light goes out then the alarm sounds.

I am guessing the sensors are trying to adjust – but not doing when outside?

Also another question, where should the sensors ideally be placed, at the moment one is fitted in each side of the dash board, just below window height – the sun does ahine on them but the alarm has been fitted to the car for the last 10 years with no problems?

Cheers

MikeyN

Hi there,

From what are you are describing above it would seem to myself that both the ultrasonics and the alarm system are both workign as they should, however the sensitivity of the ultrasonics themselves needs reducing - and this can only be completed at a Sigma dealer using a programming tool (There are notes above this thread on how to locate your nearest delaer).

The alarm system should have a red LED on the dashboard and upon arming the alarm goes through both its settle time (Where the air stabilises inside the vehicle) then its ultrasonic sensitivity set up time (Within this second timer if any movement or change in pressure is detected inside the vehicle by the ultrasonics the LED will come on briefly for a second before going back to its normal flashing red state), hen after this second timer has expired the alarm system is fully armed up ready for any possible breach of the system perhaps thorugh the doors, boot, bonnet, extra sensors or indeed throught he ultrasonics as you seem to be experiencing here. So from the description you have provided it would suggest that the LED is giving the correct signals, whilst the alarm system is interpretting what the ultrasonics are picking up whether the vehicle is inside or outside - it is just not picking up any air movement when your vehicle is inside your garage though (Colder air tempreture). You also say that the alarm is triggering when the interior lamp on the vehicle extinguishes I propose this is merely a coincidence.

As for the positioning of the ultrasonic sensors themselves they should be fixed securely towards the top of the vehicles A-pillars (The pillar running from the top of your dashboard to the roof) and they should be slightly inclined towards the centre of the vehicle, ensuring that the sun visor does not obscure the sensors at any point.

Hope this information helps, looks like a trip to your dealer will be required to alter the sensitivity, if you do require anymore information please reply to this thread or pm me at any time.

Regards

Mike.N