To engineer reliable high quality wire harness and cable components require extensive research, experience and vigorous testing. Even large OEM manufacturers and automakers are not immune from occasionally making errors in design which usually become very costly and may result in large product recalls.
While wiring component engineers thoroughly define product specifications based on application and environment in which a wire harness or a custom cable will be operating, sometimes a wrong selection of the components or a mistake in product assembly specification and an occasional engineering blunder may result in substandard wire harness assembly or cable assembly. Every so often it is hard to detect a malfunction during the testing and only after the finished product is on the market it becomes evident that the wiring component was not up to standard.
For example, according to the NHTSA (National Highway and Traffic Safety Administration), the Honda Fit model made in 2004 and 2005 had numerous complaints on low beam light malfunction. The problem seemed to go away after replacing a wire harness.
Nissan had to recall 134,215 Infinity G35 cars made in 2005-2007. According to NHTSA statement, the airbag wire harness could wear out, which could result in interference with a signal of airbag deployment during a crash. The documentation states that because the harness waspositioned under the seat, it was continuously jostled and possibly it result in wear which would allow corrosion to form on the connecting terminals, and that in turn could corrupt the transmission of the signal to deploy airbags.
In a case like this engineers should have foreseen the likelihood of wire harness damage over the period of time and redesign the component or secure it properly protecting it from being damaged. In automotive manufacturing, due to multitude of factors that have to be considered while designing every component, it usually takes longer to prototype test and develop a wiring component and the cost associated with development and engineering is high.
NHTSA also have investigated Mercedes Benz E-class on a similar case where driver’s airbag would not deploy during the crash due to faulty wire harness design. In this case some statements were made that the steering column wiring harness was too short to accommodate a full range of extension of a telescopic steering column. If that is so, this would be a very gross mistake on the part of the engineering team. It also raises a question on how this error was overlooked during the testing of the components.
Every manufacturer strives for perfection and as technology becomes more intricate the quest for quality also tends to become more complex. Therefore QC process requires a highly detailed custom approach, not only to a specific branch of manufacturing but to each individual product based on its application. Computer modeling has proven to be an effective method to detect possible defects in the design but any computer model is only as good as a programmer behind it. Therefore a blind reliance on the software produced reports may not be enough when dealing with new types of specialty cables. Engineers have to go beyond the established protocol to identify potential weak points when designing new complex wire harness or cable assembly products.