Reuse wiring harness connectors

Last update: 10/5/12
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There is a thread on the LocostUSA forum asking about reusing the connectors in a wiring harness when adapting it for a Locost.  I explained how I attach wires to the crimped connectors and am presenting it here.

This method should not be used on high current connectors.  If the solder melts the wire could come free and short out your wiring system.

First things first:

The very first thing to do is to get the metal connectors out of the housing.  Figuring out how to get the connector out of the shell is the hardest part of this whole process.

There are many different types of wiring connectors which use different methods to retain the actual metal connector in the housing.  Because there are so many ways of doing this I am not going to attempt to try to explain how to do this for any particular connector. (Sorry 'bout that.)

You'll have to try to find the manufacturer of the connector for information.  Although after awhile you will probably be able to figure out the simple connectors by just looking at them.

In general though the common connectors found on most wiring harnesses use a retainer tab that holds the metal connector in the plastic connector housing  (see picture below).

retainer tab

The plastic housing has a stepped hole that the connector is inserted into.  As the connector is inserted into the connector shell the retainer tab at first is pressed against the connector and then pops into the open condition as shown in the above picture as the connector hole steps to a slightly larger diameter.  To remove the connector the tab has to be pressed back against the metal connector so it can clear the decreased diameter of the plastic hole.  Once the tab is pressed out of the way the wire and connector is just pulled of the rear of the housing.

Generally you insert a thin probe (a dental pick or a thin jewelers screwdriver) into the area around the metal connector from the side opposite of the wires and press the retaining tab against the side of the metal connector.  You will probably have to push on the wires as if you want to push them out the front side of the connector.  This relieves pressure on the retainer tab so it can be pushed out of the way.  Once the tab is against the connector itself you just pull the wire & connector out the back of the housing.

Removal tool

This is a tool that sometimes can be used by inserting it along side of the connector to push the retaining tab out of the way.  I've had it so long that I can't remember which company made it but I'm pretty sure it's still available. The red handled portion is slightly larger in diameter than the white one.  You might be able to make one using a thin piece of a soda can.  Mine seems to be made from spring brass.

Now that we have the connectors removed from the housing here are the steps to attach the new wires:

connector crimp
This picture is NOT a typical connector used in low current automotive wiring harnesses but it clearly shows the two crimps that you will be working with.  The normal wiring connectors will be the tubular or square looking ones similar to the 1st picture.

Here's the sequence of events to connect your new wire to the metal connector.
  1. For starters only open up the insulation crimp that holds the insulated part of the wire.  The wire crimp that is actually holding the wire is normally just too hard to open up. More than likely you'll destroy the connector before the crimp is opened.
  2. After spreading the insulator holding crimps, work the wire up and down so it (hopefully) breaks off as close to the wire crimp as possible. Hold the connector with a needle nose plier at the wire crimp while you bend the wire up/down.. Or use a small wire clipper to cut the wire loose as close to the wire crimp as possible.
  3. Prepare your new wire by stripping about 3/16" of insulation off and pre tinning the wire.
  4. Lightly pre-tin the top side of the wire crimp groove where the wire holding crimp is. I usually use a wooden clothes pin to hold the metal from moving while soldering etc.  You only want to lightly coat the area of the wire crimp where the new wire will be soldered to it.  Don't apply too much solder to the joint or the connector might not fit when you try to insert it back into the plastic shell.
  5. Bend the tinned part of the wire at a slight angle to the insulated part so the insulation doesn't touch the insulation crimp tabs for the next step.  Basically don't melt the insulation when soldering.
  6. Position your new wire so the insulation will end up under the insulator crimp and the tinned part over the pre tinned wire crimp.
  7. Solder the wire to the connector. Just make a nice smooth final solder joint only where the wire lays on top of the crease of the wire crimp.
  8. Once the connector has cooled off straighten out the wire so the insulated part lays so the insulation crimp can hold the wire in place.
  9. Use a small pliers to fold the two pieces of the insulation crimp over the insulated part of the wire.
  10. Check the retaining tab that the connector uses to lock it into the plastic holder. Sometimes when you use a tool to flatten it down to remove the connector it doesn't always pop up all the way up again. I use an X-acto blade to get under it to stand it up just a little.

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