Question on wire splicing

I think a person should use whatever they are comfortable with using and know that they'll have a high success rate.

For instance, I know that my soldering skills can be best described as nonexistent, so I use crimps. But I use a tool that has a male and female feature that pins the wire in the crimp, instead of a cheapo vaguely bowlegged Crimp of Suckitude that just sort of mushes the connector a little more closed. And I pony up for the GOOD connectors that are seamless and have built in heatshrink. Yeah, they're like 50 cents each and any kind of wiring job will eat them up like a MAC-10 eats metal. It's worth it. And I tug-test every connection, hard. Better to fix it now than to fix it after much hair removal diagnosing where the problem is.

Knurled wrote: In reply to pres589: In theory yes. In practice, it's not that simple, and best practice is to not assume perfect conditions. Every automotive PCM installation that I've bothered to look into has used only one, maybe two ground points for everything related to a given system, and that point is generally on the engine itself. Generally speaking, this is the case. More and more, I'm seeing that they are going postal and sensor power and ground are all going to the PCM itself. So when I wire a standalone and certain items get their own grounds, I make sure that the ground points are all shared. It's only a little extra bit of wire and it eliminates any potential (sorry) hassle. It's actually a little less work this way, since I will gang several light-gauge wires into one heavier-gauge ring terminal.

I do it a bit differently. Keep in mind that sensor returns and sensor grounds are two entirely separate creatures! For instance, IIRC the air temp sensor on the intake on my TII motor is done by the PCM sending out a 5v ref which then goes through the sensor and then to a ground on the engine. OTOH, the air temp sensor in the MAF also uses a 5v ref but its signal has to return all the way to the PCM via a second wire, that is NOT a ground, it is a 'data return'. (I'm not looking at the wiring diagram right now so forgive me if I am wrong.) In the case of the first sensor there are also others which use the same setup so I could wind up with another five or six wires going back to the ground point. So what I did was this: I 'ganged' all those grounds to a single point on the engine block. I picked an aluminum point because generally there's less corrosion there later on. I then ran a single 10 ga ground from there to the PCM case. The PCM case is also grounded to the car body via yet another wire.

I am something of a freak when it comes to grounds, I have seen far too many weird and transient electrical problems caused by poor or nonexistent grounds. I will pay more attention to them than the power side of things sometimes. It's not just me; a bud who races an ITS Mustang just could NOT get his AFR's straight yet he had no fault codes. It turned out that the MAF ground, although it looked good, was the source of his problems. Grounding the MAF directly to the PCM case solved the problem.

Back to soldering for a moment: due to my automotive ADHD I have gone through various cars and motorcycles two or three times. (Hey, it could be worse; a friend of my dad's married the same woman four times. ) So I have had the opportunity to reinspect wiring repairs that I had done ten or even fifteen years previously, I have yet to find a solder joint that failed. I have, however, found crimp joints done with those cheapo hard plastic covered butt connectors where the wire could be twisted and then pulled out, that is a lot of the reason I do not trust them.

Then you don't use cheapo hard plastic covered butt connectors I don't think anyone here is suggesting they're a good option.

30-odd cents each: http://www.delcity.net/store/Heat-Shrink-Butt-Connectors/p_805404

Never tried them, but here's one for the belt and suspenders crowd: crimp connectors with integrated solder, so the solder flows when you heat them. http://www.delcity.net/store/Heat-Shrink,-Solder-&-Crimp-Butt-Connectors/p_805407

And the tool, $35. Mine has interchangeable jaws so I can change it up for different types of connectors. http://www.delcity.net/store/Double-Insulated-Terminal-Crimp-Tool/p_665741

BTW, about the heatshrinking portion. If you build a little rounded shield for the end of your heat gun, you can get a nice even shrink without toasting nearby wires. I built my own, sometimes they come with the guns. Looks like this, goes on the end of the gun.

In reply to Curmudgeon:

Good point re: differentiating between a sensor return and sensor ground. The modern systems I've seen have the sensor ground go to the PCM, not just sensor returns. No wonder computers have 160+ pins nowadays.

So hijacking this because that's what I do, apparently; what sort of splice hardware would be recommended for when you want to add a branching wire to an existing wire? Like you have an existing 10 gauge stranded wire in a vehicle harness and you want to make that straight wire into a Y with a 10 gauge wire and run that somewhere else. Or you want to basically make a 10 gauge wire into an insulated bus bar, effectively, and run a few daughter wires off of it one at a time so it looks like a series of Y's in a row.

I'm trying to improve some hurried repairs / improvements I made to my motorcycle's wiring harness this past summer. I realize that I could cut the harness and use insulated butt splices but that means I have to cut the wire. That's not so bad but if you have a wire that isn't cut to start with, is that still the right thing to do? Or should I get a bunch of open barrel splices like this guy;

And then go to town with heatshrink and tape?

I'd use a step-down butt connector, such as this one: http://www.delcity.net/store/Step!down-Heat-Shrink-and-Crimp-Butt-Connectors/p_805405

In order to use that open barrel splice, you'd have to strip the insulation from around the wire for a short distance. Not that easy to do. I've seen something similar in OE harnesses, though. Usually just on grounds.

In reply to Keith Tanner:

Not that hard to strip the insulation from a section of wire. Tedious though. I've done it; I used a utility razor blade when I added wiring to the bike, then punch a hole between the strands with an awl then put the new wire through that hole and around. Wrapped it and I was good to go. But I don't think that's a long lasting way to do this.

You know the wire strippers that have the secondary jaws that open up like the Predator's face and you strip the wire by squeezing the grips together?

Those also work in the middle of wires. Super fast and simple. The insulation is typically flexible enough that you can moosh out enough bare wire.

Found an image:

In reply to Knurled:

So you'd use the open barrel splice and branch off without cutting the main wire?

If I were splicing that way, actually, it would be soldered, coated with liquid electrical tape, wrapped with tape electrical tape, and the spliced-in wire ziptied to the main wire a half inch or so away from the main wire, then doubled back at the ziptie and ziptied to the main wire again an inch away.

Not that I'm paranoid, or anything.

If I didn't want to go through all that hassle, I'd just cut the main wire and double up the added-in wire to one side of a butt connector, which also works really well. And allows you to heatshrink.

Most folks don't know how to solder properly; poor preparation, inferior materials, inadequate tools, poor technique, and too much solder.

BTW, proper electrical flux is essentially inert, used properly, no removal is needed. Structural (acid-based) flux should NEVER come anywhere near electrical wiring.

Consider modern cars, just try to find a single soldered wire joint anywhere. A properly executed crimp does the job.