Thread: Sigma Alarm Help
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Old 14 October 2005, 11:20 AM
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Sigma Sam
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Originally Posted by DonnieDarko
i have a new EU import with a sigma system 4 alarm- is that M30?

anyway i have a keyfob which unlocks the alarm, but i'd prefer to use the buttons on the key instead (they seem to have been disabled)

can i reprogram the key myself/ get a company to do it (it has two buttons- open & lock, or willl they not actually set the alarm?

This is a very important point, but unfortunately a little in depth so bear with me....

The original "2 button" ignition key on non-UK vehicles is designed solely for convenience to lock/unlock the doors, with little thought to security. It does not utilize the necessary random encryption transmission required by Thatcham to switch a Category 1 alarm system.

There are Thatcham approved alarm systems on the market that are designed to be switched from a vehicle’s original equipment transmitter, but their Thatcham approval is granted only on the understanding that they are fitted to vehicles whose existing transmitters have secure encryption to Thatcham's specification.
However, as most manufacturers (Subaru included) now use transponder technology to switch their standard immobiliser systems, there is no need for them to produce an encrypted transmitter just to operate the vehicles locking - there are no requirements in this area.
Any product fitted to an imported Subaru that switches from the original "2 button" ignition key will no longer be Thatcham approved as the transmission is susceptible to code scanning and grabbing.

On early 2001 vehicles when the "2 button" ignition key was first introduced in the UK a separate Radio Key was supplied to securely switch the alarm system and meet Thatcham approval.

The batteries were deliberately removed from these early "2 button" ignition keys to prevent them from working - if the vehicle were locked with the separate Radio Key and then unlocked with the "2 button" ignition key the vehicle would unlock, but with the alarm still armed, leading to a trigger when the door was opened and then confusion over which button to press!

For UK vehicles the Sigma Radio Keys transmitter was redesigned to fit inside the Subaru ignition key housing, whilst retaining the Thatcham encryption.
As the Sigma transmitter utilizes a single button to both lock/unlock the vehicle, a new top section for the ignition key was manufactured in the UK for the single button.
If you have an early UK car (with a "disabled" 2-button ignition key and the separate Sigma Radio Key with the Blue Subaru decal) or an import with a Sigma M30, then the re-designed Sigma transmitter and single button key housing can be purchased from Subaru and programmed to your system.
The part number is SACC 3507 for these parts and should cost around £40.
Don’t pay over the odds for programming, as this can be done yourself using the keypad in a couple of minutes, provided you have the system's PIN code or an existing working Radio Key.

On a similar note, there are Thatcham 2 to 1 upgrade alarm systems on the market that are designed to be fitted to vehicles with an existing Category 2 immobiliser, but their Thatcham approval is granted only on the understanding that they are fitted to vehicles whose existing immobilization system carries Thatcham Category 2 approval.
Unfortunately, the standard Subaru transponder immobiliser has not been tested on its own by Thatcham and so does not carry Category 2 approval.
Any Thatcham 2 to 1 upgrade alarm system fitted to an imported Subaru that utilizes the existing Subaru transponder immobiliser will no longer be Thatcham category 1 approved.



I hope that may have explained things, rather than confuse you further!
In short
1. Ensure you have a full Category 1 alarm system fitted - not a 2 to 1 upgrade.
2. Ensure your system is armed/disarmed by a separate Radio Key (or the built-in single button Sigma type) – not from the original “2 button” type

SS
Last edited by Sigma Sam; 14 October 2005 at 11:23 AM.
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