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AbstractWire Harness is the interconnecting wiring in the

vehicle for the transmitting electrical power and signals in the

electrical system. Over the years the number of components to be

connected and hence the number of circuits has increased many

folds. This has made the wire-harness design as the most complicated

task in the vehicle design and wire harness (electrical system )

integration with the other aggregates a difficult job. Many CAD tools

and design software have evolved from computer companies. But

they have not resolved major issues faced by vehicle OEMs and the

wire-harness manufacturers. In fact, the requirements of vehicle

manufacturers are not clear to the other agencies and this results in

wire-harness development as a major bottleneck in any vehicle

development program. An overview is given on the importance of the

wire-harness design and the impact it will have on the success or

failure of the final product VEHICLE when it reaches the

customer.

KeywordsWire Harness, Automobile.

I. INTRODUCTIONHE increase in the electrical and electronic content in the

automobiles has resulted in the wire harness design

becoming more and more complex. From the simple function

of electrical power distribution and transmitting signals, it has

become a networking of multiple controllers with a vast range

of sensors , actuators and their interfaces. Many luxury

features used only in high-end vehicles for safety and comfort

have now become standard across all makes and models. With

the availability of more electronic components suitable for

automobile applications the gadgets on the vehicles are

multiplying with every new model introduced in the market.

II.RELATED WORKThis Procedure and Guidelines issued by NASA [1]

establishes guidelines for the Product Design Team (PDT)

providing support for the design and development of

spaceflight electrical harnesses. The P & G is marked as

COMPLIANCE is MANDATORY which signifies the

importance of wire harness design for any space mission. The

same level of weightage is being given in the field of

automotive designs as the number of safety requirements of

electrical and electronics units needs to be taken care at design

stage of vehicle development.

Mr. Ajay Pradhan is Asst Professor with D Y Patil College Of Engineering,

Akurdi, Pune e-mail:[email protected]

III. BACKGROUND DETAILA.Principles Of Wireharness DesignThe wire harness design is usually last component to be

finalized on the vehicle proto-type. Various design changes

are done to meet requirements of access, serviceability and

robust design. But the inherent flexibility in the routing and

adaptability to other system items, results in the design of wire

harness being changed to incorporate feedbacks from different

agencies.The following general principles are used in the process of

wire harness design;

- Design to cost

- Optimum lengths & routing / branches

- Protection from Thermal and mechanical damage

- Water proof or sealed connectors in critical areas to

avoid contact corrosion

- Design to assembly

- Access to serviceable parts / troubleshooting

- Design for manufacturing of wire harness

- Minimum bending radius

- Poke yoke / mistake proofing

- Splice position / joints

B.Conventional Methods Of DesignThe normal practice followed by vehicle manufacturers was

to define the overall specifications of the electrical system and

then prepare the circuit diagram for the subsystems. The

compiling of the subsystems will result in the total vehicle

level electrical circuit which will be used to design the wire

harness requirement of the particular vehicle. The following

process flow is used to define the design inputs and outputs

for this purpose;

Design Inputs

- Wire Harness Design manual- Vehicle level Electrical circuit schematic

- Layout on vehicle

- Feature list

- Component details

- DFMEA

Design Outputs

- Wire harness drawing

- Bill of material

- 3D bundle layout

- Digital interference check

Current Trends in Automotive Wire

Harness Design

Mr. Ajay Pradhan

T

International Conference on Mechanical, Production and Automobile Engineering (ICMPAE'2011) Pattaya Dec. 2011

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- Prototyping

- Validation process

IV. PROPOSED SYSTEMA.Manufacturing Challenges In Wireharness DesignIn spite of all technological advances in the field of

automotive assembly line; the manufacturing of wire harness

is still done manually and at the most using semi-automaticmachines for a few operations. The wide variations in the

layout from one model to another and also in versions for the

same model has resulted in almost no standardization of

design. Each OEM follows a different philosophy in selecting

the components and making the layout for the vehicle. [ 3]

The major challenges faced by wire harness manufacturer

in todays automotive industry are;

- Variety of connectors / terminals: The connectors are

proprietary items of the manufacturer and rarely they can be

duplicated / copied due to IPR issues. This results in no

commonality in the connector and terminal designs and at

vehicle level there is little scope to reduce the variety. Thesystems and components on the vehicle for different electrical

systems come from global sources who will not allow the

connector design changes in already validated product.

- No Standardization: Connectors used for a same function

vary across models and vehicle platforms. Similarly, vehicle

OEM should have the connector, terminal and wire standards

to bring uniformity in design and drawings.

- No regulation: Unlike the functional components as

lamps or safety components as horns, wipers; wire harness

design is not required to meet any regulatory requirement.

However, deficiencies in design can cause serious hazards on

the vehicle and protection has to be in-built for the wire

harness.

- Insufficient protection to wires: The vehicle environment

may require certain branches of wire harness with special

insulation or protection. Identifying the requirements in

advance and implementing in the design necessitates a lot of

forethought / experience on the part of the wire harness

designer.

- Manual checking of W/H: The process of wire harness

assembly uses a assembly board and at the end to the line the

connectors are manually plugged into matching components to

check the circuit continuity and correct insertion of wires. If

any fault is reported then tracking the problem and rectifying

it is done manually.Harness assemblies are becoming increasingly complex,

making the process of manual insertion result in higher scrap

rates and additional quality control issues. [4]

- Tier II suppliers of raw materials: The wire harness

manufacturer depends on a number of sources to get his raw

materials and any deviations in quality affects the final

performance of the wire harness and its reliability.

- Handling issues (Mechanical damages): The wire harness

needs to undergo many stages of handling from the

manufacturing to getting assembled on the vehicle.

B.Future Trends In Wire Harness Design :The wire harness design in interlinked with the trends in the

overall vehicle development. However, to increase the

efficiency of the wire harness design in terms of cost and time,

the use of CAD tools dedicated to the process of wire harness

design have come into the market over the years. The features

in the packages address some of the steps in the design which

were done manually or on the prototype wire harness to freeze

the design; The major highlights of the software packages are

listed below;

- Standardization and increased productivity through

design

- Modular design

- Sneak analysis / Voltage drop testing / Fuse blowing test

- Simulation of circuits

- Design rules Checks

- 3D modeling in CAD & flattened wire harness design for

manufacturing

- Recycling of wire harness material at end of life.

- Generate the BOM for the wire harness

A cost benefit analysis can help you determine when awiring harness should and should not be used. [5] [7]

C.Cad Tools Used In Wire Harness Design :Harness drawings can be produced in either 2D or 3D

format using CAD software; however, a 2D format lends itself

better to harness construction since the 1:1drawing is normally

attached to the harness board as a template. A 3D format,

while very explicit, does not lend itself to this application.

There are, however, drawing packages that produce both 2D

and 3D versions from the same native file. [5] [6]

Software packages from trademarks below are used by

different vehicle OEMs and wire harness manufacturers to

bridge the gap between design of the wire harness and

manufacturing them as per the design.

- ZUKEN

- MENTOR GRAPHICS [2]

- EMBASSY etc.

V.CONCLUSIONThe reliability of the electrical system can be gauged from

the robustness of the wire harness layout and the consistency

of the supplies received from the wire harness manufacturer.

If the controls on the assembly of wire harness ensure that the

fitment is exactly identical as per the fitment drawing

specified by the designer, the electrical faults due to wireconnections get totally eliminated. Similarly, if the quality

checks at wire harness manufacturer are enabling an error free

and zero defect wire harness, the vehicle assembly clearance

for electrical system faults will be almost nil on assembly line.

The wire harness contributes to almost 30% approximate

cost of the total Electrical system but is responsible for more

than 50% of the problems faced in the Electrical system.

Hence, the significance of the proper design of the vehicle

wire harness is self justified.


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REFERENCES

[1] Design and Development Guidelines For Spaceflight ElectricalHarnesses ; Procedures and Guidelines NASA Directive No.565-PG-

8700.2.1B Nov 2005

[2] JOHN P. WILSON, MENTOR GRAPHICS MODELING REAL-WORLD DESIGN CHALLENGES WITH MODERN VEHICLE

HARNESS DESIGN TOOLS MGC 12-10 TECH9450-w ; 2010

[3] Eli sa Pou yanne, Business dev Mgr Mentor Graphics Driving wiringharness design data toward manufacturing. Pg No. 2-11

www.cfibermfg/Wiring harness guide

[4] PATRICK BOYER, Harness Automation project Mgr, KOMAX corp.Benefits of fully-automated wire harness assembly. Pg No. 13-15


[5] Darrell Fernald, Engineering Mgr Copper Interconnect Building wiringharnesses to save costs in chassis and racks. Pg No. 17-22


[6] Jingkui Ruan; Xueliang Zhou Research on CAD/CAPP integratedsystem for automobile wiring harness Mechanic Automation and

Control Engineering (MACE), 2011 Second International Conference on

Digital Object Identifier: 10.1109/MACE.2011.5988240Publication

Year: 2011 , Page(s): 5146 - 5149

[7] Forde, C. The architecture and analysis of the XK8 electricalsystemThe Electrical System of the Jaguar XK8 (Digest No.:

1996/281), IEE Colloquium on Digital Object Identifier:

10.1049/ic:19961455 Publication Year: 1996 , Page(s): 7/1 - 711


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