Installing connectors for your wiring

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Cleaning up the mess

Let's say that your bike's previous owner mangled the turn signals connections due to his inept electrical skills. Or, perhaps you want to add some electrical accessories, but don't want the permanence of soldering. Electrical connectors are your answer.

Our project bike had lousy connections between the bike and the turn signals. The first thing is to undo the mess. Take off the duct tape, untwist the wires, and clean off the now-crumbling duct-tape adhesive. The sticky stuff attracts dust, and crumbles away once it dries up. Not the best way to insulate an electrical connection.

In fact, these turn signals had crimp-on connectors on them; the previous guy just twisted the bare wire around the terminals (red and black at bottom of photo). Yes, it will work, but it looks sloppy and isn't easy to connect or disconnect.

Molex2 02.jpg

Molex connectors

Here is the replacement: 3 pin Molex connectors. Any electronics store should stock these. 0.62" connectors were chosen for several reasons:

  • The wire gauge is correct.
  • Conveniently, this is a 3-pack of Male and Female pairs.
  • These connectors have a snap lock, making the connection strong against vibration.
  • Molex connectors are known and trusted.

Molex2 01.jpg

The aftermarket turn signal lamps have three leads, and the motorcycle's electrical connection only has 2 lines. The third lead will be uninhabited on the bike-side connector, which is perfectly OK. It could be used for a DRL line into the front signal light later. The third line will leave that option open.

These are the plastic Molex connectors. Here you can see the female connector on the left meeting the male connector on the right. The "wings" on the connector are for mounting the connectors on a PCB, or other plastic housing. As you're probably not mounting these connectors onto anything, you can clip them off.


Here are the three crimp-on terminals. Molex connectors have a spear/barrel connector. These cables are from the fairing-mounted turn signal light. The important thing is to match the crimp-on connectors. The spear terminal is the "male" of the pair. The female is the "barrel" or hollow terminal. On the floor, you'll see a yellow handled crimping tool/stripper. Nice to have, but any pair of needle nose pliers will neatly crimp these on.


Note which wire is which. It's a good habit to place the red "hot" line on the #1 line. Be consistent; it will reduce guesswork later on. On this bike all bike-side connectors will be the female connectors, and the accessory side connectors male connectors.

The last step is to put the terminals into the Molex connector. All that needs to be done is to shove the connector into the plastic. The previous image shows that the terminal tip has two prong-hook bits. This makes the tip easy to insert, but difficult to pull out.


The bike side of things isn't quite so neat.

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The wires are twisted, and a significant amount of the insulation has been stripped away. Since it was shortened to begin with, we don't want to trim this wire.

Using heat shrink tubing to cover exposed wire

Here you see that the crimp-on connector still leaves exposed wire. This needs to be covered, or else it is going to short on something.

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There are several options. One is electrical tape, which isn't the best choice because it can degrade over time (the adhesive dries out) and doesn't look as neat. There is also liquid brush-on electrical tape. This stuff (which isn't tape at all) will cover the lines, but also becomes noticeably brittle with exposure to the elements and repeated flexing. It is good for stable connections that aren't going to move.

The best option, for this kind of mess, is heat shrink tubing. Put a length of the tubing on the wire, then crimp on the connector. You'll notice that the bottom crimping part is uncrimped. Crimp that after you've secured the heatshrink tube. The top crimp clamps the connector to the copper inner wire. The bottom crimp has the heatshrink tube slid in under it, so that it will crimp down onto the insulator.

Molex2 05.jpg

Use a hair dryer or heat gun to shrink the tubing (Not a lighter). All the wires are now insulated. The middle one had nearly an inch of wire that was exposed. They are now ready to be crimped. The bottom wire shows a good angle of how the heatshrink tubing is going to be under the crimping "wing" bits. This looks neat, protects the wiring from shorts, and isn't going to degrade very easily.

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Finishing up

After crimping the bottom crimp, the terminals are installed into the Molex sheaths. The ones in these pictures are the "barrel" type receiving connectors. The barrel connectors are put into the "male" Molex connectors. The spear-type connectors are put into the "female" Molex connector. You'll notice that one of the connectors only has 2 wires. The turn signal has 3 wires, and the bike only has two, so a three-terminal connector was used to avoid dangling wires.

This is much cleaner than the original twisted together cables, and far easier to disconnect if needed. The Molex connectors have a lock piece that keeps them together, so vibrations aren't going to shake these loose.

The wing bits can either be left on or trimmed off. Nothing will be hurt either way. The middle connector in the second picture is the stock rear stop lamp connector. The new additions fit right in, and look pretty much the same, if a little cleaner.

Molex2 07.jpg

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The result is a neat connector that will stand up to vibration and is easy to disconnect. These connectors are readily available, and can be purchased very cheaply, making your bike's electrical system modular and consistent.