The two-year grace period that allowed European trailer manufacturers to retrofit a Software Update Management System expired in July 2026, and new trailers built without one can now be refused the plate required to put them into service. The requirement stems from UN Regulation R156, which took effect in July 2024 and made software update management part of the type-approval process itself. Haldex, which supplies SUMS as part of a package with its braking systems, says trailer OEMs now need documented control over every software change made to an approved vehicle. “The intention of the legislation is to maintain the vehicle throughout its lifetime in compliance with its original type approval,” says Alexander Kraus, product manager for electronic braking systems at Haldex.
Highlights
- The grace period for retrospectively adding SUMS expired in July 2026; trailers without it can be denied the plate needed to enter service
- Haldex SUMS records each trailer by vehicle identification number, tying it to the installed braking device and that device’s software level
- Braking parameters lock automatically after 311 miles (500 km), after which changes require an approval request routed to the vehicle manufacturer
- Haldex is approved to ISO 24089 for SUMS and is pursuing ISO 21434 certification for cybersecurity
What R156 Requires
R156 applies to vehicle manufacturers, not to component suppliers. Manufacturers must record the initial hardware and software state of every electronic unit on the vehicle, and every subsequent update must be documented, tested and approved before it reaches the field.
Because a supplier cannot have its systems type-approved in isolation, Haldex has instead pursued independent certification — ISO 24089 for SUMS, with ISO 21434 for cybersecurity to follow. According to the company, that certification then supports the OEM’s own compliance case.
Readiness across the industry is uneven. “Some manufacturers are much further advanced and have already certified themselves; others are still working through the legislative hurdles,” Kraus says. Manufacturers not yet ready can fall back on national individual approval rather than full EU type approval, a workaround Haldex characterizes as short-term rather than a durable answer. A companion regulation, R155, covers cybersecurity management and is not yet in scope for trailers, though the two are closely linked.
Why Does the Rule Exist?
Kraus points to tire pressure monitoring, mandatory on trailers and commercial vehicles since 2024 and connected to the braking system, which in turn feeds information to the driver. An electronic brake system supplier could in theory issue a software update that disables the monitoring gateway, leaving a legally required safety function inoperative — potentially without the OEM ever knowing. R156 is designed to close off that scenario.
Inside the Haldex Portal
Haldex SUMS runs as a web-based portal: a manufacturer registers as a company, adds its own users, and maintains a database recording each trailer by VIN alongside the braking device installed and its software level. Once logged in, a manufacturer can see every trailer it has built with a Haldex braking system and the configuration of each. “It’s a large database that records the trailer, the devices installed on it and the related software level,” Kraus says.
Security comes from locking that configuration. When the braking system is installed and set up, an operative can see key braking parameters including laden and unladen weights. Settings can be locked manually, and the system locks them automatically after 311 miles (500 km) in any case. After that, nothing changes without authorization: a user raises a change request in the field, and the relevant person at the vehicle manufacturer is prompted to approve or decline it. Kraus acknowledges the trade-off — the workflow is auditable but slower, since it requires connectivity and a human approval step.
The Haldex platform itself is not mandatory. OEMs can build their own SUMS, and some have; a few could even keep records in what Kraus calls “an advanced Excel sheet.” The catch, the company says, is that such an approach offers no automatic update notifications and no visibility into whether updates exist at all.
Cybersecurity as the Next Layer
Although R155 does not yet apply to trailers, Haldex is pursuing ISO 21434 certification regardless. New-generation hardware adds a microprocessor capable of encryption, and the company has introduced signed bootloader software, which it says verifies that software being loaded onto a device originates from the correct source and blocks manipulated or counterfeit code.
Kraus frames the risk in commercial terms: “Imagine someone hacks into your braking system and prevents the vehicle from braking, then tells you the trailers aren’t moving until you pay.”
Onboarding and Migration
Registration takes roughly five minutes, according to Haldex, after which the first user becomes account administrator and can create and edit additional users. Initial account setup runs through the Haldex service desk, which the company says aims to respond within 24 hours. A user guide sits on the portal homepage, and both initial and on-site advanced training are available.
Parts installed before the legislation took effect are not locked and can be handled as before. Parts installed and configured afterward must be brought onto the platform, with the vehicle manufacturer claiming the part as its own before the process matches a new installation, linking the trailer’s VIN to the device. Haldex describes the migration as largely automatic, but flags it as something OEMs should account for as registration becomes mandatory.
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