On the way to computers on wheels
How zonal architecture is paving the road to the software-defined vehicle
Autonomous and connected vehicles represent the next step in the evolution of the automobile. To transform this vision into reality, many manufacturers are adopting a new design approach for automotive electronics, known as zonal or zone architecture: Instead of electrifying vehicles based on hardware functions (domain architecture), zones are created based on positions in the vehicle. The advantage: less wiring, fewer control units (ECUs), greater standardisation. Current vehicles with old architecture contain up to 120 different ECUs, making the wiring harness the second heaviest component after the engine.
Fewer wires
Clustering functions in zones reduces the amount of equipment and wiring required and at the same time paves the way for software-defined and networked vehicles (SDN: software-defined networking). In zone-based architecture – which, according to consulting firm S&P, was already on board an estimated 38 per cent of vehicles built worldwide in 2024 – a central computer is connected to powerful zone controllers that manage the sensors and actuators. Electric vehicle manufacturers are leading the way.
In order to operate this kind of network, high computing power, high bandwidths and low latency are required. Autonomous driving also requires real-time network technologies such as Automotive Ethernet TSN (Time Sensitive Networking according to IEEE 802.1AS-2020). At fieldbus level, advanced or newly developed standards such as CAN FD and CAN XL, LIN (Local Interconnect Network) and PCIe (Peripheral Component Interconnect Express) are also in use.
Greater standardisation
Zonal architecture promotes the standardisation of vehicles, making it easier to integrate new modules and functions and enabling (shorter) wiring harnesses to be manufactured in an automated manner. In addition, future firmware updates and other software updates can be carried out “over the air” (OTA), i.e. wirelessly, in software-defined vehicles – provided that a high level of functional safety in accordance with ISO 26262 is ensured.
On the hardware side, powerful zone controllers and gateways (edge computing) are required, which work with highly integrated circuits (SoC: System-on-Chip). A separate operating system and so-called middleware are also needed. Middleware is software that is able to mediate between different applications or systems – for example cameras, sensors and powertrain – and organise the exchange of data between them.
Regardless of the specific design – there are also hybrid forms between domain and zone architecture, especially in the transition phase – wiring harnesses require intensive testing. The more complex the built-in functions become and the more interconnected they are, the more serious the consequences of malfunctions.
Wiring harness tests are therefore extensive and varied – and this is where INGUN’s expertise comes into play: The Wire Harness business unit provides suitable solutions for various scenarios and requirements.
The following tests are typically performed:
- Detection test: To check whether components are present and correctly positioned, switching probes are often used, which provide the desired feedback depending on the scenario (switches, signalling devices, etc.). Switch probes are available in many different patterns and as normally closed or normally open contacts.
- Continuity test (circuit test): The electrical continuity test can be carried out with inserted contact probes, but is often performed with screw-in test probes. They ensure that the test probe is firmly secured in the receptacle during the test – particularly recommended for applications with vibrations or unwanted lateral and longitudinal forces.
- Position test: This test checks whether the contact terminals are correctly positioned in the connector. Step probes, also known as collar probes, are used here. They are available in many different versions.
- Push-back test: The push-back test also checks whether the contact terminals are installed in the connector housing for reliable electrical contact. INGUN offers special push-back probes that can detect unwanted slipping of the contact terminals.
- Testing of cable lugs: Testing connectors with geometrically aligned contact terminals – such as cable lugs – requires special care. To avoid damage, the cable lug must be contacted at the front without the probe penetrating. INGUN non-rotating probes ensure precise alignment and gentle, reliable testing.
- Testing of coaxial and data connectors: Coaxial connectors such as FAKRA have a signal conductor and a surrounding outer conductor. During the continuity test, the conductivity of both conductors must be ensured – without a short circuit. The high-potential test (hipot test) also checks the insulation in order to detect faults or production defects at an early stage. These procedures also apply to data connectors such as H-MTD. Special dipole probes are used for testing, optionally also for high voltages up to several kilovolts.
- Leakage test: When wiring harnesses are used outdoors, for example in the engine compartment, reliable protection against water, dust and other environmental conditions is essential. This is achieved using seals such as tape material, cable grommets or specially sealed connectors. The leakage test checks their effectiveness by creating positive or negative pressure via test probes in airtight receptacles. Depending on the design, the receptacles are either closed or were bored and subsequently soldered.
Zonal architecture brings the automotive industry closer to the software-defined vehicle – by reducing wiring and using standardised interfaces. However, for the new concepts to be implemented reliably, the basic components, such as wiring harnesses, must also meet the highest quality standards. Extensive, precise tests ensure that safety, connectivity and durability are guaranteed. INGUN offers a broad range of testing technologies that supports manufacturers in all phases of the transformation – from classic domain vehicles to modern zone vehicles. Like this, the vision of a computer on wheels is gradually becoming reality.