Wiring harness is one the most essential parts of the vehicle industry. A wiring harness is an organized set of wires, terminals and connectors that run throughout the entire vehicle and transmit information and electric power, thereby playing a critical role in “connecting” a variety of components. Power and information travel through this network much like the circulatory and central nervous systems of the human body. It conducts electricity for all electrical loads on a vehicle.

Wiring harnesses contribute tremendously to manufacturers’ development and advancement of vehicles around the world. Automobiles or off-highway vehicles are driven in all kinds of environments, from cities to mountain villages, in the tropics as well as in cold climates. This means wiring harnesses must offer superior durability.

There are four main steps in electrical system design: selection of component, wiring diagram, wiring harness and electrical routing. Let’s look closer into these!

Selection of component

Selection of connectors, fuses, lights, switches, sensors, wires, cables, relays, protection tubes, motors etc. are the core components of the wiring harness. The performance of these components directly determines the overall performance of the wiring harness and plays a decisive role in the stability and safety of the whole vehicle. The basis of the selection of these components is the voltage system and its current carrying capacity. Ambient temperature in the selection of these components is one of the most important aspects of wiring harness design. Proper selection of these electrical components and their conductors ensures reliability and safety. For example, for the requirements of high performance airbags like ABS and ECU with a terminal connector, gold-plated pieces are preferred to ensure safety and reliability.

Wiring diagram

Wiring diagrams are also known as schematics or circuit diagrams. The selected components are placed and connected to each other in the diagram. These components belong to a set of libraries which can be modified and configured according to customer specific requirements. A wiring diagram shows each connection in detail. The schematics give an overview of the components that are part of the electrical design. Other items in the schematics are for example cables, sheet cross references and ECUs.

If an assembly is going to be used for communications or data signal transmission, twisted pairs should be considered to eliminate the risk of noise or EMI (electromagnetic interference) impacting on the performance of the assembly.

Wiring harness

There are several factors to consider when designing a cable assembly or wire harness for your application. The wiring harness is designed once the schematics are ready.

The entire vehicle is divided into parts which are detachable and the wiring harnesses are designed accordingly. This process also involves generating a connection list and a BOM (bill of materials). Harness passes through many areas where it requires protection against heat, dust, moisture etc. Wire harness protection prevents damage caused by wire vibration damage, abrasions and incidental contact with other pieces of heat-producing equipment.

Thermal management tubes and sleeves are designed to operate under high temperatures and provide superior fire resistance under extreme conditions. These tubes and sleeves are difficult to ignite, and they self-extinguish promptly. The most common types of cable and wire protection are braided sleeving, corrugated loom, heat shrink, vinyl tubing and conduit. A typical wiring harness drawing has cable lengths, component view, grommet, connector specifications and inline connectors.

Electrical routing

The lengths of the harnesses in the harness drawing are derived from the 3D models. Harness installation drawings are generated via 3D routing. The routing feature creates a unique type of subassembly which builds paths of electrical cables between the components. It ensures flexibility between two or more components and helps in deciding the path through which the cable should run to avoid further complexity. This helps in understanding the path followed by a particular harness.

Continuous development

The values of maintenance of all forms of electrical loads on a vehicle are important to achieve maximum performance from the systems. Adopting new values will ensure more safety. Maintenance can therefore be carried out by inspection, detection and repairs.

Wiring harness is currently going through an advancement phase, as well in the field of controller-based wiring diagram or CAN systems for communication between various components to check and balance their functioning, as in improving easy detection of any problem that might occur while the vehicle is functioning or in stand-by mode. Further development is taking place in the industry through automation.

Software mainly used for designing wiring diagrams and harness are Zuken E3, AutoCAD, Creo and Catia.

FOR MORE INFORMATION, CONTACT:

Arto Rajanen

Manager, Plant & Mechanical Engineering, Germany, Europe

Citec Group

Send e-mail

Phone: +358 40 750 4455