DaveEFI wrote:Err, I have a car rather younger than 40 years old which has solder joints inside the harness. In places where one wire is joined to several. A brass crimp is used to hold the wires together before soldering. Soldering a single wire to a tag etc can be a problem as the process weakens the wire slightly, so more likely to fracture with vibration. But as part of fixed harness in a car, there won't be any vibration. However, any terminals should be crimped using the correct tool, as by nature any connector is likely to be subject to at least some movement.
On the above car(s) electrical problems are quite likely with connectors. Same as with all old wiring. But yet to see one where those soldered joints have failed.
Exactly.
People keep regurgitating this worn out rhetoric of "It's been xx number of years since automobile manufacturers have used solder" as some sort of justification for not soldering. I've seen soldered connections in OEM harnesses, in recent years, they also use sonic welding or splice connections, in some cases, so sonic welding should be the go to, if you're going to cite what the OEM does, no?
You want to know why most manufactures that do use crimping methods use them? It saves time, which saves money, period. Crimped connections can be repeated quickly and easily to a high degree of quality, and that's the long and short of it. Crimping is NOT a superior electrical connection or less prone to failure than soldered connections, period. Typically (properly) crimped connections will last longer than a warranty period and that's about all they care about anymore.
There's a lot of myths floating around about soldered connections being brittle, or causing the wire to fail where the solder joint ends. I've been working with automotive electrical for 30 years or so and have NEVER seen anything that could back up these claims, for a soldered joint to failed where a crimped one wouldn't. I've had to dig deep into many harnesses, both OEM and aftermarket, either for finding a problem or modifying/splicing into an existing circuit. Any failures of connections I've seen would have failed using either connection method, because most of those failures were caused by corrosion (where a crimped connection likely would have failed sooner than a soldered connection) or by some physical interaction with something else, driveshaft, axle, steering shaft, engine pulleys, axe, vehicle hitting a wall or other vehicles, etc. I have yet to find an unsupported soldered connection fail, and I've come across a few just hanging out in the breeze, though I don't condone this lack of wire support, more on that later.
I've had to fix many crimped connections though done by amateurs, because they used cheap crimpers and didn't understand how to make a proper crimp, which brings me to the next point. When someone suggests crimping, it should be IMMEDIATELY followed up with "Using a proper crimping tool, for the wire size and type of connection being used". No, those $2 crimpers you got at the convenience store will not give you a proper crimp. I have several different types of crimping tools, some costing a few hundred dollars to be able to have a proper and strong crimp for the times when I need to use just a crimp, such as some terminals that don't allow the connection to be sealed with solder. Yes, I like to solder crimped terminals where I can to provide a seal against moisture, especially under hood connections or where moisture is likely.
ANY connection, soldered or crimped should be supported, so this claim about unsupported soldered connections failing is just a red herring. Bundling wires together into a harness will ensure that the harness supports itself, regardless of which type of connection method you choose. Tying a harness to solid structures (usually inside loom) is a great way to support wires to ensure that there are no failures from movement, however, a harness should have SOME slack in it for chassis movement and twisting, temperature changes and in extreme cases where the power being conducted will actually cause the wire to move, which is not typical in an automotive environment though.
Proper solder techniques do take practice and unfortunately I've met some people that no matter how much practice they had, they should just never pick up a soldering iron/gun. There are tutorials on how to make good string connections using solder and what types of solder to use for what applications.
But I digress...
When it comes to splicing multiple wires together, it depends on a few things, like the actual application of those circuits, how many wires need to be spliced, where they will be physically running between available space how much current will actually be conducted on them.
In the case of sensor grounds, the current is typically very low, and the wires will run relatively between the same two points, ECU and engine. In this case I will typically run one main sensor ground out to one of the sensors and then tap into the wire by striping a little bit of the insulation off and wraping the additional circuit around (sometimes I will poke the new wire through first) and then soldering it. If I planned it right I will have some heat shrink on the connection as well, otherwise high quality electrical tape over the splice wrapped tightly (typically I use the tape on add ins and reworks, not new harnesses). Sometimes I will bundle 3 or 4 wires together coming from sensors and then connect these into a single wire to go back to the ECU. It kinda depends on how the harness is being laid out and space available along with where the sensors are relative to each other. In a recent harness I made for my T-Bucket, I had a few sensors that went into separate sub harnesses, and went back to a large feed through connector in the floor. I spliced the sensor grounds together several inches away from this main feed through to bring it down to 1 wire and then ran that single wire on the other side of the harness back to the ECU. I have 13 grounds running through that main connector even with the sensor ground splicing!
I have in one case where the harness path was tight and needed to lay a certain way spliced in several sensor grounds splicing in each one every couple inches apart nearer the ECU. It was time consuming to do it this way, but it was the best approach at the time.
For the main grounds where they are connected to the ground point (battery or engine block, depending on who you listen to or prefer here), I will typically brong all of the grounds together into a single ring terminal, in the case f 10 of those 13 grounds I used an 8 AWG ring terminal for ten 18 gauge grounds, stripped them all long, and crimped them in the ring terminal. After crimping using a razor cut the excess wire off that is above the ring and then solder the end to cap it and provide another bond. Finish with heatshinking the wires and terminal for additional moisture resistance and strain relief. I'm attaching a couple pictures of this connection specifically.
In other cases where grounds are split to many different locations or for higher current circuits I do use buss bars/distro blocks, but these are typically not EFI related circuits.
I'm not a fan of those Y or X crimp connections because they take up a lot of space for something that doesn't need to, and again I prefer soldering connections... ;)
