How to Repair Car Wiring

Learning howto  repair car wiring and splice wires is an important skill you will probably need someday. With time and practice this skill can be mastered and is useful and necessary for those looking to be professional automotive repair technicians or make DIY repair jobs themselves on vehicles. With automakers adding more sensors, electronics, and gadgets to cars chances are one day you will have to make a wiring repair, whether you want to or not.

For those unfamiliar with the procedure of repairing a wire I'm going to walk through how repair car wiring simply and easily.

Step 1 – Strip Wires

First you want to strip back ¾ of a inch on the outer insulation of the wiring on each end you will be connecting together. (The inner metal part, usually made of copper, is called the conductor as conducts electricity.) It's best to use a wire strippers that have various sizings on them for small wire repair. These can be purchased in most hardware and auto parts stores and are a great addition to any toolbox.

Remember to size and cut a piece of shrink tubing and put it on one of the wires before twisting or soldering them together. If you forget, you will have to take apart or re-strip the wire connection later to put a piece of shrink tube on the spliced and soldered part of the wire. If you fail to put a shrink tube on it will likely cause more damage to the wire from corrosion.

Step 2 – “Y” Wires

Now that the wires are stripped, take one of the wires and make two equal but separate connections with the copper strands and form a “Y.” Repeat with the other wire and then join them together interlocking the two wire ends and twist them together. When joining the wires together it is best to use one finger to hold down the legs of the “Y” on the same side on a table or flat surface. Pick-up one wire so it it at 90 degree angle to the other wire and start twisting rotating together. Try to keep the connection as snug and tight as possible.

If this is done properly there should be no gap or a very small gap between the copper strands and it should be a fairly tight connection. Also it should not be or that much larger than the outside diameter and gauge of the insulation of the wiring.

Make sure to leave enough room so that the outer insulation “none” strip sections of the wire can bend without too much trouble. You can repeat this using your other hand and twisting the other side of the wiring. It should be a strong connection even if without soldering or using shrink tubing yet. Lightly pull it to see how the connection feels.

Note: They are many methods for twisting car and auto wiring together.  This is just one way to do and certain automakers and manufacturers might have different techniques.  

Step 3 – Soldering Time

At this point you can get out a soldering gun. Nowadays most automakers recommend a butane-powered soldering gun that uses a flame for heating the tip. Soldering with an electric soldering gun is generally note recommended nowadays as it can possibly send voltage back through the wire and damage a sensitive electronic component.

Before beginning make sure the wire flux you are using is rosin-core NOT acid flux. If you use acid flux you will wreck the wiring since it will corrode down the road. I also recommend you wear protective goggles. You never know what debris could fly up at your face and into your eyes while soldering.

Once your gun is on, and your goggles are on too, touch the soldering gun to the splice and let it sit for 30 seconds to 1 minute. You should be able to to see when it is getting hot. Take your flux wire and carefully let the solder flow at the junction of the gun tip and splice. Put the flux too close to the gun tip and it will “stick” but if it is too far away it won't heat up enough.

Once it solder is flowing keep adding and pushing the flux wire and creating more solder. It will flow around and onto the copper wiring strands and you want to make sure there is enough on there. You might need to move the gun depending on the size of your wiring repair.

The solder should look nice and shiny when done. If it's dull looking you will have to reheat it since it was not hot enough. Try to give it a nice shiny appearance.

Step 4 – Shrink Tubing

After you've let the solder joint cool, and admired your work, it's time to get use that piece of shrink tubing on the wire and complete the repair. Heat shrink tubing is made of polyvinyl chloride (PVC) or polyolefin and will shrink around the wire protecting it from the elements and corrosion.

The best way to shrink the tubing around the splice to use a heat gun. Typically butane-powered soldering guns have an attached just for this. The tubing shrinks when enough heat is applied and will seal and conform to the shape of the wire.

The quick and dirty method is to use a lighter, but be aware that can possibly cause damage.

Step 5 – Check for Continuity

It's good to check for continuity that the wiring and circuit is working properly. You can use a multimeter and set it to read “Ohms” so that you know the wire actually works.

Car Wiring Repair

Learning how to repair car wiring is something that sounds hard, but once you have the basics down it will be become more natural. There are other methods you can use to repair automotive wire. Crimping is another popular method but many automakers nowadays don't like auto technicians or people using this method since crimps can pull apart.  Also it can leave your solder joint susceptible to the elements and corrosion.

Whatever method you use check what the manufacturer recommends of the vehicle you are working on.  If you ever need help remember there are lots of resources out there to help with wiring and electrical repair online nowadays.

If you have any questions, tips, or advice on car and auto wire repair please leave a comment below.

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Adam loves cars and anything with wheels. He has many interests and passions but he especially loves writing and blogging. Hence starting this auto blog.

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Adam loves cars and anything with wheels. He has many interests and passions but he especially loves writing and blogging. Hence starting this auto blog.

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