Sunday, 9 April 2017

Car wiring harness best practice... or not?

What inspired me to write up some notes was a question posted on Facebook. The answers to which were conflicting. How do you know which answers are the correct ones and which are wrong or just not the best solution.

That got me asking, what is best practice for car wiring harnesses?

It proved more difficult than expected to get a satisfactory answer.
Apparently racing teams use aeronautic or boating standards.

This is one of the most commonly quoted references that I found:

I fairly regularly come across people fixing car wiring with a soldering iron. Even my local garage was going to solder on some bullet connectors. They did admit that at the time they were lacking an auto-electrician. You can probably tell that I think solder for this use is a bad thing.

I was taught that solder on stranded wires was a bad thing if the cable was likely to move. Mechanical vibration causes the solder to crack. If the stranded cable is free to move it would be undamaged. That pretty much applies to the entire loom in a car, by my thinking.

My best evidence for not using solder joints is that all car looms I have seen in the last few years have been exclusively crimp connectors.

So I have not found the definitive answers I was hoping for. Therefore I am left to draw my own conclusions.

In my opinion:

  • Do NOT use solder joints
  • Use crimp connectors
  • Use butt splice crimps to join wires

If I come across any more definitive answers I'll update this article.




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