Tech Tips

How to Fix Broken Wiring

Written by  July 31, 2005

We are faced every day with all kinds of hazards, either the 90-year-old white- haired grandma in the car or debris in the road that we don’t see until we hit it with our bikes. But what about the loose, chafed or plain broken wiring that is causing shorts or blown fuses? I think it is safe to say that we must fix these ourselves or have it done by the local shop.

If you choose to have this done in the shop, great! Otherwise you can attempt to tackle this job and get the results that you need to fix any or all wiring issues.

I suggest that you identify the circuit through the wiring schematic in your service manual, thus not to solder something to the wrong circuit and cause a fire or completely melt the wiring harness and leave you stranded. Repairing the wiring can be challenging, yet rewarding. I have worked on certain bikes that should have been put to rest many moons ago, and I have found that this can be time consuming and requires great patience.

You need to isolate the break or chafe. When this has been identified and if removal of the component can be done, you can take that piece to the workbench and solder the piece that is damaged. I do recommend using a good wire stripper to clean the plastic or cloth sheeting on the wires. Having the wires stripped correctly by size according to the gauge on the stripper is a key to having a solid connection after the tinning process.

The wires that are going to be soldered need to be prepared beforehand. Strip ¼-inch of insulation from the end of the wire, and tightly twist the exposed strands. When splicing smaller gauge wires such as switch or receiver harnesses, always tin the two ends and twist them together before applying solder to the joint.

Splicing a harness wire will make the spliced wire shorter than the other wire(s) in the harness. When the harness is pulled, all of the shear stress will be on the shorter wire, so it is imperative that the mechanical connection be strong. Be sure to insulate the exposed wire connections to prevent shorting. Re-twist the harness to take up the slack in the longer wires and improve the overall strength.

I want to stress the following items:
Apply enough solder so that every strand in the twisted tip is surrounded by solder.
Do not over-tin the wire or the solder may flow up under the wire's insulation causing it to become rigid and you will end up with globs of solder on the wire ends that will have to be removed.
If you are going to splice the wire to the middle of another wire, strip away the wire's insulation from the area to be soldered to, and tin this exposed area just as you did with the wire end.

Another thing that needs to be addressed is the use of soldering guns. The secret of a good solder is to use the right amount of heat. Too little heat will result in a cold solder joint; too much heat can seriously damage a component. The key factors in quality soldering are time and temperature. Generally, rapid heating is desired. If heat is applied too long, the flux may be consumed and surface oxidation can become a problem. Recently they have introduced a newer style soldering iron called Cold Heat. I have not used it but for those who have, please let me know how it works! I usually use the traditional soldering iron that can be purchased from Sears or any good electronics store.
When it comes to wire strippers, I prefer the automatic type that can be purchased from Snap On or Mac Tools. I, however, use a manual wire stripper, and it works great in tight places where the auto cannot be used.
I prefer to lace the stripped wires and twist outward toward the plastic; I find that it is much easier for the solder to melt and the joint is almost unbreakable. I normally slip a piece of shrink tubing onto the wire prior to twisting the two halves together; however, sometimes the wire that I am fixing is pretty short. You must be very careful not to heat the wire up so hot that it collapses the shrink tubing before the required position. This will have to be re-soldered and may cause grief. The outer casing is really thin and will melt with excessive heat.
After you have soldered the wires and they have cooled, you can pull the shrink tubing over the repair and heat with a good heat gun. Heat guns are preferred due to the gasoline and oil that is present in our bikes.
The last thing you must check is the strength of the joint. Firmly grab the wire on both sides of the repair and pull firmly away from each other; if the wires are strong you are finished. Feel better?! This repair will be strong and last a long time without concern. I have rated this tip on the tough-o-meter scale a whopping 4 due to the tools and your skill level. This is not for everyone so I suggest you practice on some scrap wire before going the distance. And always remember to use the same gauge wire when replacing—you will be glad you did.
B-safe out there!
By Dave Miller