Electrical systems can be daunting.
My first suggestion, pick up a book on motorcycle electrical systems, (Haynes makes a decent one)
And pick up a decent multimeter. and use the web to understand how to use it.
Use the book to understand the wiring diagram of your bike.
Then it's a really good idea to go over the whole system and clean every contact, switch and terminal.
I use dielectric grease on any contact that is solid, so no switches and I only use it on relays after they have been plugged in.
I use 1000+ grit sandpaper, pencil erasers and metal polish to clean connections. You want to remove the oxidization but not the plating of the terminal unless you have no other choice.
There are some products out there that are designed to clean up these connections, but I've not had good luck in these products getting the connections clean while not attacking paint, plastic or rubber. So I just do it by hand.
I've used alcohol on a q tip as a solvent, and canned air or an air compressor to clear things out.
If there are any connection that have gotten too hot, you need to understand why, and fix the problem.
You will see this as burnt, discolored or melted connections and or wires.
Corrosion = Resistance = Heat. Heat increases the speed of corrosion, and the cycle gets worse and worse.
Relays go bad, or more likely there's enough resistance in the wiring and plugs that they get garfed up.
I've found that new relays have solved a lot of the really weird or random light, horn, turn signals issues I've had.
One thing to remember, BMW likes to do things their own way and they love their special (and expensive relays)
So it's best to make sure everything else in the system is clean and solid and good connections before going in and replacing relays.
On vacation for a spell
squish screwed with this post 12-02-2012 at 11:22 PM