I am going to have to get under the back end of the truck and fix all the connections done by the previous owner as everything is corroding from the salt and water getting in there. I was going to solder the connection and then cover them with maybe a paint on electrical tape? Or I was also thinking about using the heat n shrink tubes with some silicone injected into the tube but that sounds messy. How do you protect your connections?

 

I use the heat shrink tubes,then use silicone around the ends of the heat shrink to seal it off.

 

I usually use crimp bullet connectors with dielectric grease and shrink tube the whole assembly. Soldering under the truck is a pain.

 

using an iron or a station would be a PITA under the truck, though if you have a gun with a light that might work well. If you can get a good connection and a good solid solder joint i'd say go ahead w/ the solder and then heat shrink that. I've never thought of using silicone, but on the ends sounds like a good idea. Just remember to put the tubing over the wire before you make the joint. If you don't have a gun id' say double end crimp terminals would be a good next choice then. Just make sure to have enough stripped off to make good contact, but not so much that its harder to crimp, and it just slides out, or can corrode easier. Again i'd put the shrink tube over that as well.

 

Experience has shown and proven again and again that you never use "crimp on" connectors anywhere outside the cab of your truck...even if you heat shrink and silicone them...your just asking for electrical issues down the road...at least up here in the great white north. They might work down in California where there's no extremes in temp. or road salt.
Solder them and do it right. It helps if you "tin" the wires first when they're hanging down, then slide the heat shrink over the wire first like someone said earlier. Use a small alligator clip to hold the wires together while you solder them. Having the wires tinned already speeds this up.
If your having a hard time getting the solder to "suck" into the wires, try cleaning the wires first with a dab of flux. Make sure you burn out all the flux first with the tip of you iron. You'll be amazed at how fast the solder sucks into the wire if you do this first. Try this on a piece of wire on your work bench first...without flux first, then with.
Like someone else mentioned, put a little smear of dielectric grease on the joint before you put the heat shrink over it.
You'll never have to look at your wiring back there again if you do this...you will if you use crimps, guaranteed.