Hi,
I have the following problem on my 1986 FLTH. While driving, many times the the dashboard lamps shot off, there is no turn signal and no rpm. All of a sudden it comes back, then it is ok for a while then the same thing. I found a contact over relay under the seat. If i hit it carefully (of course when the bike stopped with running engine...) everything comes back. It is obvious to change it. But i would like to know what does this relay do exactly.
thanks
Andy

 

Most of the time a relay exists to be able to deliver high current to different circuits. A low power circuit usually activiates it and that is your switch or it may be hot all the time. So on your relay you should find:

A small wire that supplies the power to activate the relay. It way be activated by power or ground. Another small wire that would complete that ciurcuit. These are usually identified as X1 and X2.

The remainder of the relay will be the switched circuits and depending on the number on contacts you'll have power sitting at some of the terminals and no power on the others.

It is simple enough to jump power from one side of the terminals to the other to actuate the circuit and see what they do.