GeoKontrol 2 for Diesel Vehicles: GPS Geofenced Speed Control

Traditional speed limiters set a single maximum speed for a vehicle — typically the national or regulatory limit. But fleet operations rarely involve just one speed environment. A diesel truck might travel on motorways at 56 mph, through towns at 30 mph, past schools at 20 mph, and across depot yards at 5 mph — all in a single journey. A fixed-speed limiter addresses the top-end limit but does nothing for the lower-speed zones where vulnerable road users are most at risk.

AutoKontrol’s GeoKontrol 2 solves this problem. It is an IoT GPS-enabled speed control device that automatically adjusts the vehicle’s maximum speed based on its GPS location. When a diesel vehicle enters a defined speed zone — a school zone, a residential area, a construction site, or any custom geofence — GeoKontrol 2 reduces the maximum speed to the level set for that zone. When the vehicle leaves the zone, the restriction is released.

No driver intervention is required. No telematics subscription is needed. GeoKontrol 2 is a standalone device with its own GPS receiver and cellular connectivity for zone updates.

How GeoKontrol 2 Interfaces with Diesel Vehicles

GeoKontrol 2 connects to the diesel vehicle’s accelerator pedal signal — either the analogue DBW voltage signal or the SENT protocol signal, depending on the vehicle — and to the CAN bus for vehicle speed data. It also contains an integrated GNSS receiver that provides continuous position data.

The device stores a database of speed zones — both standard zones (derived from speed limit data) and custom zones defined by the fleet manager through the GeoKontrol web portal. As the vehicle moves, the GNSS receiver continuously compares the vehicle’s position against this zone database.

When the vehicle enters a zone with a lower speed limit, GeoKontrol 2 adjusts the maximum throttle demand that can reach the ECU. On a diesel vehicle, this means the fuel demand signal is capped at the level needed to maintain the zone’s speed limit. The ECU responds by limiting fuel injection, turbo boost, and power output — the vehicle simply will not accelerate beyond the zone speed.

The transition is smooth and progressive. The driver feels the throttle become less responsive as the zone speed is approached, just as with a conventional speed limiter. When the vehicle exits the zone, full throttle authority is restored within seconds.

Technical Considerations for GeoKontrol 2 and Diesel

Zone Transition Accuracy

GPS accuracy in open environments is typically 2-3 metres, which is more than sufficient for zone transitions on roads. GeoKontrol 2’s firmware uses zone boundary algorithms that account for GPS positioning uncertainty, ensuring that speed changes happen at the correct point — not prematurely and not late.

In urban canyons, tunnels, or heavily built-up areas where GPS accuracy may be temporarily reduced, the system uses dead reckoning based on CAN bus speed data and last known position to maintain zone awareness. When clear GPS signal returns, the position is updated immediately.

Diesel Turbocharger Response During Zone Changes

When a diesel vehicle transitions from a higher-speed zone to a lower-speed zone, GeoKontrol 2 progressively reduces the maximum throttle demand. The diesel engine’s turbocharger responds to the reduced fuel demand by reducing boost pressure, managed entirely by the ECU. This coordinated response prevents any adverse effects on the turbocharger or exhaust aftertreatment system.

The transition from a lower zone back to a higher zone is equally smooth — GeoKontrol 2 gradually restores full throttle authority, and the turbocharger spools up naturally as the driver increases throttle demand.

Custom Fleet Zones

Fleet managers can define custom speed zones through the GeoKontrol web portal. For diesel fleet operators, common custom zones include depot yards where vehicles should not exceed 5-10 mph, customer delivery sites with site-specific speed restrictions, distribution centres and loading bays, school zones during term time, hospital and care home access roads, and construction sites with temporary speed restrictions.

Custom zones can be created, modified, or removed remotely through the web portal. Zone updates are pushed to GeoKontrol 2 devices over cellular connectivity — there is no need to physically access the vehicle to update zone data.

No Telematics Dependency

GeoKontrol 2 is a standalone IoT device. Unlike solutions that depend on a fleet telematics platform to function, GeoKontrol 2 carries its own GPS receiver, zone database, and cellular modem. It does not require a separate telematics unit, a telematics subscription, or integration with an existing fleet management system. This makes it straightforward to deploy across diesel fleets of any size, including fleets that do not have telematics installed.

Exhaust Aftertreatment Compatibility

Because GeoKontrol 2 works through the accelerator pedal signal — allowing the ECU to manage all engine outputs — diesel exhaust aftertreatment systems (DPF, SCR, EGR) operate normally throughout zone transitions and speed-limited operation. DPF regeneration, AdBlue dosing, and emissions control functions are unaffected.

Real-World Applications

Urban Delivery Operations

Diesel delivery trucks and vans operating in urban areas regularly pass through 20mph zones, school zones, and pedestrianised areas with restricted speeds. GeoKontrol 2 automatically enforces these lower limits without relying on driver awareness or compliance. For operators with duty of care obligations — particularly those delivering to schools, hospitals, or residential care facilities — this automatic enforcement provides a demonstrable safety measure.

Construction Site Access

Diesel trucks accessing construction sites typically face strict site speed limits — often 5-15 mph. GeoKontrol 2 can enforce these limits automatically using custom geofences around the site perimeter. As soon as a truck enters the geofenced area, its maximum speed is reduced. This removes the reliance on signage and driver compliance for site speed safety.

Depot and Yard Operations

Fleet depots handle significant vehicle movements in confined spaces shared with pedestrians, cyclists, and other vehicles. GeoKontrol 2 can enforce very low speed limits within depot geofences, reducing the risk of manoeuvring incidents. When the vehicle leaves the depot, normal road speed limits apply automatically.

Multi-Client Logistics

Logistics operators serving multiple clients may face different site speed requirements at each delivery location. GeoKontrol 2’s custom zone capability allows the fleet manager to define site-specific speed limits for every client location across the network, all managed centrally through the web portal.

Residential Area Protection

Diesel trucks operating in residential areas — waste collection, building supplies, home delivery — can be automatically speed-limited to 20mph or lower in streets where vulnerable road users are present. This is particularly valuable for operators seeking to demonstrate corporate social responsibility and compliance with local authority expectations.

Compliance and Regulation

GeoKontrol 2 can serve as the vehicle’s primary speed limiter for regulatory compliance, or it can operate alongside a conventional fixed-speed limiter to add location-based speed control. For vehicles subject to ECE Regulation R89, the fixed upper speed limit can be managed by GeoKontrol 2 while also providing the variable zone-based limits that go beyond regulatory minimums.

Professional Fitting by SGH Connect

SGH Connect, our UK-wide fitting network, installs GeoKontrol 2 on diesel vehicles at your premises. Installation includes connection to the accelerator pedal signal, CAN bus integration, GNSS antenna mounting, and initial zone configuration. Fitting is completed within 5 working days of order confirmation.

All AutoKontrol products are 100% designed and manufactured in the UK to ISO certified quality standards, supported by over 41 years of speed limiter engineering expertise.

Get Started

If your diesel fleet operates across multiple speed environments and you need more than a single fixed speed limit, GeoKontrol 2 provides intelligent, location-based speed control without telematics dependency.

Contact AutoKontrol for a free, no-obligation quote and discover how GeoKontrol 2 can protect your drivers, your fleet, and the communities you operate in.