Reusing Plastic Wiring Plugs
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This page explains how to reuse plastic wiring plugs (aka, connectors) by extracting the metal terminals, connecting the new wires to new (or the old, if needed) metal terminals, and putting it all back together again. This is important if you are doing some re-wiring work in an existing vehicle - splicing wires together in the middle of a wiring harness is messy and generates extra heat in the harness. You want to use a single wire between each connector when ever possible - and the tricks explained here can help you do that. This is the single most important trick you need to know if you want to make a custom wiring harness and make it as reliable and good looking as possible. The second most important trick is to not use sticky electrical tape to re-tape the harness, but to instead use the proper tape or loom for your era of vehicle. Many cars use a non-sticky vinyl harness tape, others use split loom, others use a fabric tape, and some really old cars use a woven tube that protects the harness. But, that's a subject for a different page.

Eventually I'll add more pictures to this. The pictures of the Packard 56/59 terminals below are from an old Ron Francis' Wire Works online catalog. Once upon a time I tried to photograph some of the connectors and terminals I've used, but my camera refused to focus up-close enough to show the details that I wanted to show. So, for now what's here is what's here. Also, this page was originally written exclusively for the Packard 56/59 series of connectors and terminals, but has expanded since then as I've worked on different wiring systems and learned about them. The basic principles are the same, but the details can differ a lot, so be careful and work slowly until you are sure you know what's going on with your particular connector. Even on the same vehicle, it is not uncommon to encounter different style connectors in different areas of the wiring, so don't assume they are all the same.

 

Cautions and Comments

First, the warnings and cautions. You're going to be working with old and possibly brittle plastic connectors that will likely be dirty, grimy, and hard to see clearly. They'll probably be attached to the car in a hard to get to and/or hard to see location - wiring is a glamour-less thing, and it's tucked away in all sorts of obscure and hard to see/reach places that love to accumulate grime. You're going to be removing pieces that are designed to go in and not come out on their own ever again. If you mangle the plastic parts (aka, the connector bodies), you're potentially in big trouble because replacements parts for the plastic parts of the connectors are not easy to come by for most cars. I have been told than some of the more interesting and hard to find connectors on GM vehicles (such as the main firewall connector behind the fuse block) are available through International Harvester/Navistar - they use the same parts on their vehicles and they sell everything individually. The terminals are readily available in many cases, once you find the supplier for your particular style of terminal. See my Automotive Electrical Connectors page for more details. There are many different shapes, sizes, and designs of terminals out there, and you need to use the right ones for your application as well as the exact removal technique for each one.

Not all connectors have replaceable terminals as are described here. In particular, some 60's era Ford electrical systems used terminals with rubber plugs molded right over the terminals. These are impossible to replace with new wires and terminals, and splicing wires or a complete change-over of the wiring to a different style is required. My 1964 Ranchero has wiring like this - which is how I found out about it.

Now, the good news. If you do this right, no one will be able to tell what you did - at least not easily. It looks factory and most importantly works like the factory intended for many years to come. The appearance of exposed wiring (such as in the engine compartment) is a critical thing in how nice your engine looks when you open the hood, and the techniques here are one way to achieve a nice look. If you want to go for the "sleeper" stealth look, then this is your ticket. If you want to just do a clean job without cutting and hacking, this the set of how-to instructions for you. The terminal removal methods are all pretty similar - there's only so many possible designs for these sorts of things, and once you get the gist of it, you can figure out similar connector/terminal designs pretty easily.

All of this information is provided without any warranty or guarantee as to it's applicability to your situation. This is all "for informational purposes only" and if you decide to try and use this information on your vehicle/project/whatever, and something goes awry - it's not my fault. If you do not agree to these conditions, please erase all knowledge of this page from your brain and...what were we talking about?

 

Overview and Terminology

Each wiring connector on your car is made up of two plastic pieces (the housings) - one male and one female. Inside those housings are one or more metal terminals (usually brass) that the housing orients so that they will touch the proper terminal on the other half of the housing but not anything else. The internal metal terminals also have male and female pieces. The male housing usually contains female terminals - this is so the housing can properly enclose the terminals to reduce the chance of one of them shorting out. The housing is designed to ensure the connector stays together and all of the terminals touch each other so they will conduct electricity - even after 50 years or more, they should still be doing their job.

The basic idea here is to disconnect the two halves of the connector and then remove the desired terminal from one (or both, if needed) of the housings. You can then remove the existing wire and attach whatever length and color of wire that you need to the terminal (or to a new terminal if you can find the right style) and put it back into the housing in the original location. Once you put the new wire inside the existing wiring harness and plug the connector back together, the change is almost invisible and just as functional as if it was done at the factory. The only hint is that the new wire will be cleaner than the original ones, but a few months time usually takes care of that problem too. :-)

 

Terminal Retention Methods

There are separate procedures for removing male and female terminals because they tend to differ in the ways they are retained in the housing. This is very important to understand - this is the tricky part of the entire process and this is where you will usually screw something up. Take your time and do it right - mangling the housing by acting like a gorilla won't help you much. The forces involved here are very small - think delicately. If you have to force it, you're probably not doing it right - stop and double check yourself.

The common details are that these terminals are designed to be connected to the wire (via soldering, crimping, or both) and then inserted into the housing from the back. You will be accessing the terminals from the front of the housing (the part the faces the other half of the connector when it's fully assembled) to attempt to "un-clip" them and slide them out the back of the housing. The terminals are designed to resist the force of the two halves of the housing being clipped together (this tends to force the terminals towards the back of the housing) as well as the force of the connector being pulled apart (this tends to pull them out the front of the housing.) You are just seeking to reverse the installation procedure by gently holding open whatever clip holds the terminal in place while gently pulling the wire and terminal assembly out the back of the housing. Once it starts coming out, the rest is easy - it's the first 1/8" or so that's the hard part.

 

Removing Packard 56/59 Male Terminals

The male terminal is a flat "blade" about 1/4" wide. It has a slot cut in it from the back (towards where the wire hooks to it) running almost all the way out to the tip. At the base of the blade there are tiny projections that stick out about 1/16" and hold the terminal in the housing. There are tiny depressions in the housing that these projections clip into and prevent the terminal from moving forwards or backwards in the housing. That slot acts like a spring - when the terminal is inserted into the housing, the slot closes just enough to allow those projections to slide into the housing - as soon as those projections hit the depressions in the house, the slot expands back to normal size and the terminal is held in place. Look at the picture above to get an idea of what I'm talking about. When you look at the housing with the male terminals in it, this is all very easy to see and access before you remove the terminals. Compared to the female terminals, the easy visual and physical access to the male terminals usually makes them much easier to remove.

What you need to to is use a pair of small pliers to gently squeeze the terminal from the sides and close the slot enough to that those projections will move out of the depressions in the housing and allow the terminal to slide back. You must also take care to center the terminal in the housing as you attempt to remove it - if you "close the slot" to make the terminal thin enough to slide out, but you still force one of the projections into it's matching depression - the terminal will not come out of the housing. Close the slot with gentle pressure and wiggle the terminal out slowly - once it comes free it will slide the rest of the way out easily. Even though this sounds obvious, make sure that your pliers are not pressing against the front of the housing as you attempt to remove the terminal. You're working with very close tolerances here.

 

Removing Packard 56/59 Female Terminals

The female terminal  is a bit more complicated. It has to wrap around the male terminal, guide it into place, and provide some sort of "spring" to ensure they always touch each other - all without making the connector overly hard to connect and disconnect. The way it does this is by being a "u" shaped (if you look at it from the "front" end of the housing) to wrap around the male terminal and a folded over front edge to help guide it into place. It also has a small piece of it's main section bent up slightly to force the male connector to ride against the inside surfaces of the "u" shape and keep a good contact. This entire assembly must be retained in the housing against the same pushing and pulling forces the male terminal has to contend with. It does this with two separate systems - one for the push and one for the pull. (Luckily, we only need to worry about the push system for removing the terminal.) Since it has more surface area (when viewed from the front of the housing) the "pull" force is handled by having the hole in the front of the housing be slightly smaller than the terminal is so that it cannot slide out the front of the housing. The "push" force is handled by a small piece of the connector that is bent out at a slight angle to act as a spring. When the terminal is pushed into the housing, this projection will pass over a small raised area or over a small depression in the inside of the housing. It will them push outward into the depression such that the "end" the the metal spring piece is now too wide to allow it to move back out of the housing. You can't see it in the picture above because it's on the "bottom" of the terminal and the widest part would be towards the back of the terminal where the wire attaches to it.

What you need to do is figure out where that small projection/spring is at, and gently force it towards the main body of the terminal while we push the terminal out the back of the connector. To do this you should use a small jeweler's screwdriver (the kind you use to tighten screws on eyeglasses and such) or a small set of dental-style tools. You will need to insert your very thin, small tool into the housing from the front, slide it down along the terminal, find the small projection/spring, and gently force it towards the terminal while you pull the entire terminal and wire assembly out of the back of the housing. It's a bit tricky, but if you take your time you will find the right place and it will come right out. Be especially careful of forcing these out - it's very tempting to put a lot of force on the plastic housing by using the small tool as a pry-bar. Don't do this! Be gentle and don't force it. The housing can be permanently distorted - or worse yet crack and break - very easily.

 

Removing/Installing Terminals on a Connector with a TPA

Many more modern connectors, especially the various weatherproof ones, have what's known as a "TPA" - a Terminal Position Assurance. It's basically a small plastic piece that is wedged into the connector someplace (usually front/inside of the connector, but also on the back on some designs) to lock all of the terminals in place. On these types of connectors, the terminal is usually held in place with a small plastic "spring clip" on the connector body, and that spring clip cannot be moved out of the way unless the TPA is removed first. Look for a brightly colored plastic piece in the middle of the inside/front of the connector - they are usually easy to spot. Others have the TPA at the back of the connector and it clips into place. Once the two connector halves are assembled and connected together, it is virtually impossible for the TPA to come out and let the terminals fall out of the connector unless the connector body itself is compromised or warped, and even then, it's pretty hard for anything to come apart. On older style connectors, the individual terminals could come loose on their own, so this is a big improvement in connector design from the Packard 56/59 style designs that date back into the '50s - I have them on my 1958 Buick, for example. The more modern style of connector with a TPA, and often having weatherproof seals, became popular in the 80's on many cars (added reliability helped ensure less service calls and repair work and longer warranties which sold more cars), and most modern connectors use this basic design quite a lot. If you work on any fuel injected, you'll see this style of terminal.

The disassembly sequence is to remove the TPA (usually by gently prying it out with a small screwdriver or pulling it out with small needle nose pliers), then use a small screwdriver to push the plastic spring slip aside while pulling on the wire/terminal from the back of the connector. The terminals slide out very easily once the TPA is removed.

The assembly sequence is the reverse of disassembly - push the needed wires + terminals in from the back of the connector body, and when all of them are in, push the TPA into place. It's really that simple.

This style of connector, and the ease of removing/installing wires, makes changing wires in the harness with this style of connector very easy - which is a very good thing for service and repair work on the wiring in today's vehicles with very complicated wiring systems. Messed up connectors are not uncommon, and being able to remove wires and put them in a new connector quickly makes for a fast and high quality repair. It also makes these connectors easier to machine assembly in a factory when there wiring harnesses are made. This eases of removal/installation makes custom modifications easy as well, which is important to folks like myself.

Here's a Ford "wedge lock" connector with wiring attached. The red piece in the middle between the terminals is the TPA.

FordWedgeLockConnector1.jpg (1607092 bytes)

This is a Ford weatherproof connector, with a mini-wedge lock style pins. The TPA is the red piece in the center of the pins, and you can also see the red sealing gasket that is along the inside edge of the connector barrel. That seals the connector from dirt, moisture, etc. when it's connected. You don't need to remove this gasket to remove the terminals - it can stay in place.

FordWeatherproofConnector1.jpg (1606668 bytes)

Here are Ford weatherproof and wedge lock connector bodies without any terminals or wires. The TPA is below each connector body, and at the top left is the flexible gasket that the wires and terminals go through to seal the back side of the weatherproof connector body. You generally will need to pull the rear gasket out to remove more than one terminal from a weatherproof connector, though sometimes you can get the terminals in and out without removing the gasket. Note that GM weatherproof connector designs normally use a separate gasket to seal each wire opening, and the gasket is often crimped to the terminal. Ford and others use this separate one piece gasket design. In the second photo you can clearly see the plastic tabs that hold each terminal in place - these are what you gently pry away from the terminal to allow the terminal to slide out the back of the connector.

FordConnectorParts1.jpg (2711396 bytes) FordConnectorParts2.jpg (2714168 bytes)

 

Connecting New Wire to Terminals

This is the easy part. Just insert the new wire and crimp the connection down. If the terminal has an extra set of crimp "fingers" to grab the wire back by the insulation, don't forget to crimp them down too. If the gasket on your particular weatherproof connector needs to be crimped to the terminal on each wire, don't forget to put it on the wire first, then crimp the terminal to the wire, and then crimp the insulation + gasket onto the terminal. Use a quality "W" crimping tool instead of the simple "oval" ones if at all possible - they make a much better connection. The "W" crimp tool has a small projection on one side joint to force the wire inside the joint to make better a better connection with the terminal. Always put that pointed side of the tool away from the "open" side of the terminal when you crimp it down. Many specialty terminals have special crimpers to make the "perfect factory recommended" crimp on them - if you can get these, or a reasonable imitation, do so. A good crimp really is in the tool you use to make it, and the different between a good crimp and a bad crimp is night and day. A good crimp is weather-tight and will hold up as well or better than the wire itself. A bad crimp will come apart after a short bit of vibration or wire movement.

If your terminal doesn't have any way to crimp a wire onto it, or you want to be really sure it stays connected, you can carefully solder the wire to the terminal. Soldering is easy to learn but takes a while to master, but the nice part is that it's hard to really screw things up so bad that they can't be used - or at least salvaged. Your local Radio Shack is a great source for all kinds of soldering supplies if you need to get some. Be aware the soldering can make the wire end brittle and prone to break just behind the soldered point. The military specs crimps only (no solder) for all it's connections for a good reason - a good crimp is way better than a typical solder joint. A good solder joint can be almost as good as a good crimp, and if the crimp is questionable/borderline, the solder can be a help as long as the vibration level of the connector isn't terribly high. Stuff mounted directly to the engine or transmission can vibrate a good bit, especially if you are driving at high speeds, doing off roading, or engaging in "timed speed contests". Use good judgment for your needs.

You may need to wrap a small piece of electrical tape around the crimped/soldered end of the terminal so that no exposed wire or metal sticks out past the back of the housing once it's all assembled again. If so, now is the time to do it. Don't go nuts with the tape - a single layer of tape will generally do just fine. If you use too much, the terminal and wire assembly may not fit into the housing properly because it's too large. Heat shrink tubing can work well here if desired. Weatherproof connectors (ala, the GM WeatherPak series of connectors) will not use tape or heat shrink tubing, they will have some kind of rubber seal of their own that needs to be installed - follow the directions/usage/pattern/example for your specific connector to ensure it stays sealed and safe and dry - and working. Some of the GM weatherproof (also known as "sealed") connectors require you to crimp the rubber seal for each wire to the back of the terminal, it's basically crimped at the same point where the insulation crimp goes on non-sealed terminals. Some of the Ford and other designs use a single common rubber seal with multiple holes in it for each of the wires pass through. Once all the wires are in place in the connector, the seal is pushed down over the wires and into the back of the connector to seal the back side of the connector. The basic idea is the same - provide some way to seal the connector against water/dirt/grime - and they work quite well for such a simple idea.

 

Removing Old Wires From Old Terminals

This is really tricky option - if you need to re-use the old terminal you just removed, you will need to remove the existing wire from it. If at all possible, get new terminals and use them instead. Save the old wiring in case you ever want to return the vehicle to it's original condition. Use your existing terminals as a comparison to make sure any new terminals you buy are going to work properly. Only try and re-use the old terminals as a last resort - if at all possible, get new terminals and use them. They are usually cheap enough to make this a plausible option, though you may have to look around a bit to find the right ones for your needs. See my Automotive Electrical Connectors page for some ideas and help identifying what you have.

Your terminals may have wire crimped or soldered on - maybe both. (If it's soldered, you're getting pretty desperate to try and save the terminals, but it can be done...) If present, you need to remove any solder first by heating the joint with a soldering iron and using a "solder sucker" to remove as much solder as you can. If it's not crimped, the wire will fall off at this point and you can move on to connecting a new wire to it. If it is crimped, you will need to un-crimp the joint as detailed below while applying heat to the joint with a soldering iron. Unless your luckier or better than I am, you can count on burning your fingers a bit on this one (no pain, no gain?), and most likely ruining the terminal in the process. Like I said, you should buy new terminals and use them - it's much easier. :-)

To un-crimp a joint, you just need to carefully bend back the metal pieces that were crimped over the wire. Be careful not to over-stress or break them as you will need them to crimp a new wire to the terminal later on. Use a small jeweler's screwdriver or "dental pick" type of tool to get things started and work from there. Once the wire is loose, you can pull it out and gain some more working room to pry the metal crimp open far enough to put a new wire in it.

 

Putting it all Back Together Again

This is the no-brainer part of things. You take your freshly connected terminal and new wire assembly and push the terminal into the back of the proper slot on the housing until it "clicks" into place. The male terminals are usually not directional - just match any other terminals already in the housing. The female terminals are usually directional - the only fit properly one way. Either match the other terminals in the housing already, or look very closely inside the housing to figure out which way it goes.

After you get all of your new terminals installed in the housing, you should test-assemble the two housing pieces to be sure they fit properly - the new terminals may need to be wiggled around a bit to get everything to go together properly. Again, be gentle and take your time. The connector should slide together pretty easily. Once it's together, you can put your new wire into your harness as you see fit. The connector is ready to be assembled and put back where it belongs and you can concentrate on the rest of your wiring efforts.


Comments? Kudos? Got some parts you'd like to buy/sell/barter/swap? Nasty comments about my web page so far? You can email Mike or Debbie.

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Page last updated 01/02/2009 01:51:39 PM