High standard electrical connections

There are many threads on internet fora (forums) about performing electrical modifications to cars. If you are serious about what you are doing and you want the installation to be reliable you need to have the right tools, the right parts and the right attitude.

I can't provide everything in a single post so this is by way of an introduction.

ScotchLocs:
In my opinion these are totally unsuitable for a high quality permanent installation. They are a type of connector called an Insulation displacing (IDC) terminal. They work best on solid core wires, as found in telephone and Cat5 Ethernet wiring. The vast majority of car wiring uses multi strand wiring and IDC terminals simply move the strands out of the way resulting in a relatively poor contact. Use too small a scotchloc and you can cut the strands of the wire causing a permanent hazard, too large an item will make for a poor connection or even no connection.

Insulated terminals:
These are an excellent means of making a secure connection, providing the correct tool is used to crimp them. Crimped terminations are reckoned to be better than solder in most cases. Insulated terminals should be used in conjunction with heat shrink sleeving where a water resistant connection is required.

Un-insulated terminals:
Again an excellent means of making a connection and necessary for adding items to fuse boxes, obviously the correct terminals and tools are required. Un-insulated terminals require a different crimper from insulated ones. Again heat shrink sleeving can be used to reinforce the joint if required.

Tools:
Wire strippers:
If you want to make a high quality connection a decent set of wire strippers is essential, the best types have specific dies for each size of wire. Many cheaper tools tear the insulation instead of cutting it or will damage the wire strands. Once stripped the wire strands need only be twisted slightly to restore the natural twist imposed when the wire was manufactured. Twisting the strands tightly together will make for a less secure connection because it doesn't allow the terminals to be crimped correctly.

Wire cutters:
Side cutters are the most reliable but buy the best you can afford, cheaper ones don't cut the insulation cleanly.

Hot air guns:
If you plan to use heat shrink sleeving (probably called heat shrink tube in the USA) use a hot air gun to shrink it into place, a soldering iron isn't really suitable. Hot air guns are cheap and effective.

Crimping pliers:
You should use a ratchet type plier to ensure a consistent, high reliability, termination. Crimping pliers without a ratchet tend not to be closed tightly enough and result in a poor, easily disturbed connection.

Please feel free to ask questions.

Better late than never part 2
Soldered connections.
Many people have the mistaken idea that a soldered connection is the best possible electrical connection. This is unfortunately only true if the joint is made well and that usually requires holding the parts firmly and having the soldering iron at the right temperature. Joining two wires together outside in the rain is pretty much guaranteed to result in a poor connection. If you are in a nice warm, comfortable workshop with a bench and good light it is possible to make a high quality soldered connection relatively easily.

Fairly obviously, if the original connection was soldered any repair will need to be soldered. On a Saab it is likely that the solder used was lead based, if you need to buy new solder it will be lead free. When making a repair it is going to be easier if the majority of the old lead based solder can be removed. Use of a de-soldering tool should result in a clean surface, there will always be some left, making a good joint with new solder should be no different whether lead or lead free solder is used.

A good, mains or battery, soldering iron is essential but it doesn't have to be very high powered, I use a 15W iron most of the time. There are tutorials on YouTube so I won't even attempt to describe how to solder.

Types of connections
Splices
A splice is, if you hadn't guessed, a joint between two ends of wire. The best way to join a wire, most likely because it has broken for some reason, is to use a butt splice something like these https://www.amazon.com/Glarks-Electrical-Insulated-Terminals-Connectors)/dp/B01ECFP38C/ref=sr_1_20?crid=37A0Y4DCHY181&dchild=1&keywords=electrical+splice&qid=1612460502&sprefix=electrical+spl%2Caps%2C259&sr=8-20
Why crimped not soldered, simply because the skill level required to make a good crimped connection is less than that for a soldered connection, the tool ensures that the crimp is made correctly. Additionally, crimped connections, made correctly, are more consistent and reliable. Not to mention that the linked splices are insulated. They do need to be covered with an adhesive heat shrink sleeve to be waterproof..

Spade terminals
There are both insulated and uninsulated male and female spade terminals available. I would suggest using the insulated variety where ever possible simply because they use the same crimpers as butt splices. Uninsulated terminals need to be crimped using the correct pliers which are not as easily found as those for insulated terminals.

Connector pins
Most connectors in cars use uninsulated terminals which have retaining devices either in the connector or on the terminal. There are too many types to list but if you need to replace pins (male or female) the details can be found on-line together with suitable pins, crimpers and insert/extraction tools.

Superseal connectors
These are a waterproof multi-pin connector used in many more recent cars. If you are installing a new item of equipment they are an ideal way to make it readily removable should that be required. They do need a fairly expensive crimping tool but do make for a professional job. Unfortunately they aren't common on Saabs.