TOPIC:

Now just from searching through here I think I have found out that the small black factory sealed box behind the left side cover is the brake light failure switch. Is that correct? It has three wires out of it.
Under the right side cover next to the fuse panel is another sealed black box, a little bigger but also with three wires. What is this part?
Is there a way to test them with a multi meter? Where can I find replacements if necessary?

forgot to mention bike is a 78 KZ650SR.

On mine, the two electrical things with three wires coming out are:

1) Brake light failure sensor

2) Turn signal flasher unit

I didnt know there was a turn signal flasher unit, I knew there was a turn signal relay and a hazard relay, both round with two metal tabs coming out - pretty much a simple relay I assume, using a multi meter set to continuity, you should not have continuity between posts unless they are turned on, or closed

tgutz wrote:

I didnt know there was a turn signal flasher unit, I knew there was a turn signal relay and a hazard relay, both round with two metal tabs coming out - pretty much a simple relay I assume, using a multi meter set to continuity, you should not have continuity between posts unless they are turned on, or closed

A relay can not have only two terminals. There has to be two terminals for the main current path and one or two other terminals for the drive to the coil which closes the contacts. A round can with two metal tabs is probably a flasher unit of some kind.

Inside a flasher is a bi-metallic strip which bends when it warms up from the current flowing through it (then bends back when it cools), so it works with only two terminals.