The Sigma S30 is a highly regarded, insurance-approved Thatcham Category 1 vehicle security system. Manufactured by Scorpion Automotive, it serves as a combined alarm and dual-circuit immobiliser. It is widely recognized for its robustness, making it a popular choice for retrofitting into older cars, classics, and commercial vans that lacked factory-fitted security, as well as replacing outdated systems.

Here is a comprehensive breakdown of the features, security protocols, and operational capabilities of the Sigma S30.

Core Security & Architecture

The system is built around a concealed Electronic Control Unit (ECU) protected by physical countermeasures to withstand targeted tampering.

• Dual-Circuit Immobilisation: Features two independent engine immobilisation circuits (rated at 18A continuous / 30A max). These passively arm a set period after the ignition is turned off, ensuring the car cannot be hotwired even if the vehicle is left unlocked.

• Physical Attack Protection: On the S30, the immobilisation relays and internal wiring plugs are encased in a heavy-duty steel housing secured with anti-tamper screws to prevent thieves from physically bypassing the circuits under the dashboard.

• Perimeter Monitoring: Dedicated independent circuits monitor all entry points—including positive or negative switched door inputs, plus independent bonnet and boot triggers.

• Intelligent Ultrasonic Interior Protection: Cabin movement is monitored via adjustable ultrasonic sensors. The system features self-adjusting sensitivity that scales dynamically if minor environmental disturbances are detected during its threshold cycle, minimizing false alarms while maintaining tight interior security.

• Closed-Loop Protection: An extra, continuous loop wire circuit allows owners to secure external accessories. If this loop is broken—such as someone disconnecting a trailer, a roof rack, or a bike carrier—the alarm triggers instantly.

Hardware Component Package

A standard Sigma S30 kit includes the following hardware essentials:

• 2x Single-Button Radio Keys: Weatherproof, shock-resistant fobs utilizing a high-security 66-bit random code encryption. This rolling-code technology actively blocks radio frequency scanning and "code grabbing" tactics used by modern thieves. Lost or stolen fobs can be permanently wiped from the ECU's memory.

• Data-Linked, Self-Powered Siren: A compact, high-output electronic siren connected via a secure digital data link to the main ECU. Because it contains its own internal backup battery, it will continue to blast at full volume even if a thief cuts the primary vehicle battery wires.

• Multi-Function Keypad: A distinctive dashboard-mounted backlit keypad. This serves as the programming node, diagnostic tool, and physical PIN override station.

• Tri-Colour Status LED: A visible dashboard light that displays the current arming state, acts as an active visual deterrent, and flashes specific error codes for diagnostics.

Key Theft Protection & Keypad Functionality

One of the S30's standout configurations is its protection against key-theft and carjacking. If a thief steals your actual physical car keys, they still cannot drive the car away if this mode is enabled.

Key Theft Protection Mode: When active, pressing the remote fob will unlock the doors and turn off the perimeter alarm, but it will not disarm the engine immobiliser. The driver must manually enter a unique, secure 4-digit PIN into the dashboard keypad before the ignition circuit will release and allow the vehicle to start.

The multi-function keypad also allows the user to execute deep system changes and diagnostics directly from the driver's seat:

• Sensor Deletion: You can use the keypad to isolate and temporarily turn off the ultrasonic interior sensors (useful if leaving a pet in the car or parking on a rocking ferry) while keeping the physical door and boot switches fully armed.

• Battery Voltage Check: Typographic code sequences typed into the keypad read out the current charge state of the vehicle battery via the status LED.

• Diagnostic Memory Recall: If the alarm went off while you were away, you can use the keypad to identify exactly which zone (e.g., driver's door, bonnet, or interior ultrasonics) triggered the event, along with a timestamp of how much time has elapsed since the trigger.

Convenience & Programmable Logic

The microprocessor-controlled logic inside the Sigma S30 supports a wide range of convenience variables that can be customized by the installer or owner:

FeatureOperational LogicFull Central Locking Control (CDL)Built-in relays completely manage the vehicle's central locking. Pulse lengths are fully adjustable, supporting double-pulse triggers or custom delays required for vacuum or older mechanical locking retrofits.Auto-Arm / Auto-RearmCan be set to automatically lock and arm the vehicle 60 seconds after the last door is closed (preventing accidental walk-aways). If the vehicle is disarmed via the fob but no door is physically opened within 60 seconds, it automatically locks down again.Total Closure OutputHolding down the radio key button upon arming can trigger an output wire to roll up windows or close an electric sunroof automatically (requires compatible vehicle modules).Path Finder / Courtesy LightingProgrammable outputs can illuminate the vehicle’s headlamps or internal cabin lighting for a set period upon arming or disarming to guide you safely to and from your vehicle at night.Auxiliary Function MappingFeatures low-current (200mA max) negative outputs that can be mapped to trigger external pagers, extra internal sirens, window closers, or remote boot-release solenoids.

Emergency Override Protocol

If a radio key fob gets crushed, drops into water, or suffers a dead battery, the vehicle can be unlocked manually using the physical door key (which will trigger the siren). The user can silence the siren and completely override the immobiliser using one of two secure methods:

1. The Keypad Method: Punching the master 4-digit PIN directly into the dashboard keypad.

2. The Ignition PIN Procedure: If a keypad is damaged, the ignition key can be cycled On and Off a precise number of times corresponding to the digits of the system's unique PIN code to disarm the unit and allow emergency driving.