How to Modify Vehicle Wiring - Starting with the DO NOTs

[SoCalMonty]

I have to say...the OP failed to list the absolute best connectors out there.



...rock solid connections, totally rattle-proof, and *reusable*. If the wires are already stripped, you don't need any tools (crimper). You can also use them as taps by putting 2 wires in one end. Butt connectors will pull apart before these do. They are expensive, but IMHO, worth every penny. I hate having to use anything else now.

Old package:


New package:

 

[Treenail]

This fellow has some good How-To articles:

http://www.pbase.com/mainecruising/terminating_small_wires

Tom

 

[craig333]

Good advice. When I do use crimp connectors I only use ones the heat shrink ones.

 

[Ozrockrat]

3. Crimp Connectors

View attachment 180317

Don't get me wrong, I love a good crimp-on connector, but there is a right way (detailed later) and a wrong way to use them. If you follow the instructions on the packaging and only use mechanical crimping force to secure the connector, you are asking for intermittent electrical problems as well as potential connection failures. This could lead to inconvenience, blown fuses, or (worst case) electrical/battery failures.

Again, my bumper lighting kit came with non-weatherproof connectors, so I will be cutting those off, sliding on the rubber "gaskets" in the picture, stripping the wires, crimping AND soldering the connectors,

Any connection done without the proper care, knowledge and tools is prone to failure!!!!

I disagree with both the statement about using only mechanical force to secure the connector and the use of solder on crimp connectors. An insulated crimp connector is designed to provide both electrical connection and mechanical support for the connection (barrel). That is why they should always have a double crimp, 1 for the electrical connection and 1 to hold the insulation within the support collar. Preferably done at the same time with a twin die crimper. The electrical connectivity of crimp connections has been proven to be more effective and durable than solder without the added potential chemical reaction. Solder flows under mechanical stress. This is why you never crimp a soldered connection. And soldering a crimp connection only opens the joint up to chemical reactions and moves the hard point further along the cable (solder wicking) moving the flex point out past the mechanical support provided by the connector (effectively creating a single conductor instead of a multistrand flexible conductor). Soldering crimp connectors used in a connection blocks also creates the potential that the terminal will not correctly seat in the retainer within the terminal block allowing for movement and a potential connection failure.

My suggestions are:

1. Buy a good ratchet crimping tool to suit the connectors and cable you are using. Preferably one that does both crimps (electrical and mechanical) at the same time.
2. Buy quality crimp connectors. i.e. military spec ones with a medal collar in the outer portion of the connector to better retain the crimp on the insulation.
3. Use additional protection where required. i.e. if it needs to be waterproof use the adhesive heat shrink. 3M vulcanizing tape is also a bonus.
4. Practice and test your connections. Cut them open with a hacksaw and check how well they are done. Keep practicing until you get it right under controlled conditions and hopefully it will be right when you are hanging upside down under the dash working by the light from your cell phone .
5. When you have had enough practice find someone with a Rover and practice on that. They always need a bit of help in the electrical department
6. Leave the soldering iron/torch in the box. Unless you know what you are doing and have the right quality gear and solder. It has its place but IMHO that is for inline connections within a wiring harness that will be well protected and free from any movement or mechanical stress.
7. If you find an aircraft mechanic with a soldering iron in his toolkit do not fly in any aircraft he works on.
8. Leave the $20 for 500 crimp terminal kits on the shelf at the tool supply place. They are very low quality (but still better than a lot of solder jobs)

Do the military solder there crimp connections in their planes, tanks etc?? Do they use solder connections at all (except PCB's)? NASA seems to do OK with crimp connections (hopefully a bit better specified than grabbing the out of the Harbor Freight discount bin). Caterpillar, Komatsu, P&H etc all use crimp connections. How many high voltage/high current terminations are soldered these days.

Just for reference I spent 15 years starting as an electrician - technical and then going into reliability engineering on mine sites around the world. Much tougher conditions than most of our vehicles will ever see. And after studying a lot of failures we took the soldering irons off the mechanics/technicians and supplied them with quality crimpers and terminals. The soldering stations we used for any bench repairs were worth about $500 each and were calibrated yearly. Actually our big cable crimpers were calibrated yearly as well. We still got failures but no where near as many.

This is the style of ratchet crimper I am talking about. But they are crap connectors/lugs.



And a quote from one of my old engineering textbooks.
"Compression crimping forms the terminal barrel and conductor into a strong, almost homogeneous unit, producing excellent conductivity, low temperature rise, and outstanding resistance to oxidation and corrosion."

 

[1leglance]

Good to hear that a nice ratcheting crimper and quality connectors are ok as I suck at soldering...especially upside down and under a dash

Lucky for me I know a good batch of high quality PEOPLE like Bevin-Ozrockrat & Nick-Nobin..among others that have the knowledge, skills and tools to get a project down right.

 

[Big_Geek]

Just stopped back in for a quick check and found two pages of replies! What a great discussion and I appreciate all of the reference material and experience provided in the follow-up posts. I took photos of a connector installation I completed today and will post a reply with (what I consider to be) the right way to get the job done.

 

[4x4junkie]

I dunno, I've been soldering all of my connections for 35-some years now. Never have had a single failure that wasn't attributable to the wire being pulled on or stressed in some way, even on connections exposed to the elements. Yet I HAVE had crimped connections of all sizes fail on more than one occasion.
I see no reason for changing my ways.

any chance you could elaborate? I've asked guys I work with, and gotten 1 explanation I could grasp, but think there's a whole lot more to it.

if 12 volts power is going to a 12 volt device (horn? lights?), what's the need?

A relay makes for a much shorter route to get 12V power to whatever device it is your powering (most often aux lights) so you don't have as much voltage drop (no need to run thick wiring through your firewall to a switch and then back out again). It also eliminates the switch itself having to carry the full load of the circuit (which many switches are incapable of doing reliably, even in spite of having "sufficient ratings").

 

[Big_Geek]

NEVER cut into the factory wiring harness to connect accessories. Always come off the battery with an accessory fuse block to build new circuits. Having to repair hay wired factory wiring sucks.

I have had to cut into my factory wiring to get certain signals (like blinkers when installing bumpers with lights), but for powering circuits I agree.

 

[Big_Geek]

any chance you could elaborate? I've asked guys I work with, and gotten 1 explanation I could grasp, but think there's a whole lot more to it.

if 12 volts power is going to a 12 volt device (horn? lights?), what's the need?

I think of a relay as a remote switch. When I send it the correct signal (sometimes power, sometimes ground depending on the specific relay), it causes things to happen in other parts of the vehicle. The biggest problem a relay can solve for you is using small amounts of power to control large amounts of power. For example, many off-road lights can pull 10 amps of power each for a total of 20 amps when in use. Running that much power into the cab of the vehicle, using a heavy-duty switch, then routing that back out to the lights makes that power travel a lot further than it would if it simply went from the battery to the lights. That distance causes the voltage to drop which, in turn, causes the amperage to increase. That means I have to use even thicker wire to safely handle the load. The longer the distance, the thicker the wire. If I use a relay, I only have to run enough power through the switch to cause the relay to operate. This is usually a significantly smaller amount of juice. Less amperage, the relay is less senstive to voltage drop, etc... So, I hook power into my relay, hook my lights into the output, send the appropriate signal through a switch in my cab and all of the higher power functions take place remotely under the hood with much greater efficiency.

 

[Big_Geek]

I have to take issue with the 'no butt-splice connectors' and 'no crimp connectors' - there are places for these when done right, with the right connector and the right equipment.

The telecom world is held together with 3m scotchlok butt connectors, and it is harder than you might think to solder wires together.

This is true, but there are a few differences between your examples and mine:

1. Most telco wire is solid core as opposed to stranded.
2. Telco cabling is not usually bouncing down the road.
3. The crimp connectors used in the telco world are far superior to your average butt-splice connector.

In the example shown (crimped spade connectors on the back of a switch) are you seriously suggesting soldering it???

Call me crazy, but I would absolutely solder that. I would also use heatshrink tubing on the wires and over the female blade connectors to prevent shorts and blown fuses.

 

[redneck44]

In the marine and space industry crimp connectors are the preferred choice on anything except very small electonics cable.
Lloyds and DNV specify that if you want to solder a connection then it must be crimped first.
The space industry vibration test everything before launch under much much harsher conditions than any vehicle will ever see.

 

[southpier]

the relay information is helping me grasp it; thanks

 

[verdesardog]

As a 20 year US Navy electronics tech that worked on comm gear and in engineering spaces (also nasa certified miniture repair) and several years manufacturing aircraft wiring harnesses I have to say the both soldering and crimped connections have merit. It just depends on the instalation. The main problem with soldering is wicking of the solder up the strands under the insulation which causes brittleness, not good for vibration stress. Crimping quality terminals is my prefered way to do vehicle wiring.

 

[toddz69]

A lot of good info here on soldering and crimping. I saw at least one other post on it but thought I'd add that in addition to the good practices of the actual connections themselves, also consider the routing/support of wiring in the vehicle to minimize problems.

One problem I've noticed a lot is lack of stress relief in wiring - it doesn't matter how well you soldered or crimped that joint if the wire is as tight as a banjo string. Give it enough stress relief so there's no stress from its mounting.

Use zip ties (QUALITY ones - I prefer Thomas and Betts) at strategic locations to bundle and support harnesses/wires/bundles. Adel clamps are excellent for supporting longer spans of harnesses.

Use wire loom, woven wrap, etc. at appropriate locations to help shield wiring/harnesses.

Make sure wiring is well supported/covered where it goes through holes and across sharp edges. Most wire insulation is teflon, which will cold flow when sitting on a sharp edge. In the space industry, teflon wire is prohibited and we use tefzel (cross-linked) insulation which is much more abrasion-resistant and doesn't cold flow.

Todd Z.

 

[FordGuy1]

There is a reason why the connections in OEM looms and in Race cars connections/splices/terminals etc are crimped.