How do modular wiring harnesses support zonal architectures?

Vehicle wiring harnesses without a zonal architecture can have over 1,000 wires connecting over a hundred ECUs. They are difficult to fabricate and install, and changes can be difficult and costly to implement. However, using modular wiring harnesses in zonal architectures can overcome those challenges.

A zonal architecture places electronic control units (ECUs) in multiple physical zones throughout a vehicle. The various zones are connected through gateways or zonal controllers. This approach supports the continued electrification of vehicle functions without increasing wiring harness complexity.

In a zonal architecture wiring harness, wire lengths can be shortened by optimizing device locations. Functional integration can reduce the number of wires. The close placement of ECUs can facilitate the use of new types of conductors, like flat flexible cables, and enable higher levels of automation in harness assembly and placement.

Robots can more readily install lighter and smaller modular harnesses. Increased automation can lead to higher levels of precision and performance. Sub-harnesses can be incorporated into a modular architecture to enable more customization without a corresponding increase in cost.

While the primary purpose of a zonal architecture is to simplify the vehicle communication structure, the modular wiring harnesses can also distribute power and provide direct control to loads like sensors, motors, and lighting (Figure 1).

Figure 1. Zone controllers (black boxes) manage power distribution and data traffic in limited areas, minimizing the complexity of wiring harnesses. (Image: Leoni)

Communication optimization

Modular wiring harnesses can also be optimized to support various communication needs. Zonal gateways consolidate the data from the associated sensors and ECUs. They can forward the combined data to the central computer using high-bandwidth Gigabit Ethernet, such as IEEE 802.bu (1 Gbps) links. The central compute modules can be linked using cabling optimized for 10 Gbps (IEEE 802.3ch).

Fast Ethernet (IEEE 802.3u) can support applications like cameras and radar that benefit from 100 Mbps speeds. Other applications like the sensors and motor control can use slower connectivity like 10BASE-T Ethernet, controller area network (CAN), and local interconnect network (LIN) that run over unshielded twisted pair (UTP) cabling. Displays and cameras can be linked using a flat panel display (FPD) link that uses coax cables to deliver 15 Gbps of data and control signals and enables video bandwidth of more than 25 Gbps over two cables.

Figure 2. Modular wiring harnesses and zonal architectures combine to provide optimized communication support for specific functions. (Image: Texas Instruments)

More benefits

Modular harness designs simplify and speed up troubleshooting and maintenance compared to traditional wiring harnesses. Using the traditional approach, the harness in each car is complex and different. That complexity increases the possibility that implementing a repair can have unintended consequences and break an unrelated function.

Zonal architectures and modular harnesses make tracing, localizing, and correcting faults easier. The zonal, modular approach also simplifies updating or adding functions to cars.

Modular harnesses’ smaller and simpler designs also reduce the costs associated with harness fabrication and installation. Traditional wire harness production is a labor-intensive process that is difficult to automate. Harnesses can differ in small details to support specific functions and options in a car.

The simpler designs of modular harnesses enable higher levels of automation in fabrication, reducing costs and improving accuracy. In addition, installing modular harnesses is inherently simpler and amenable to being automated.