Topic: FIXED: Explain to me like I'm 5 how ignition switches work?

[PennyDreadfuls]

My 75 550k has a little brother, a 1975 360T that has a dead tail light, the brown wire power lead is dead (the brake light works fine). I stole a power lead off the flasher and the tail light lit up fine so I know there's not a problem with the bulb or rear wiring harness and there's continuity in the brown wire from the that wiring harness above the rear fender all the way up to the ignition. When I check for voltage on the brown wire coming out of the ignition switch, it's dead.

So it appears that the problem is the ignition switch but that's where my knowledge ends. Can someone explain to me how the ignition is suppose to work so I can determine if this is fixable or if I need a new ignition switch/key etc...?

[Jerry Rxman Griffin aka MuthaF'er]

Simply put it connects 2 'leads' to allow power across to complete the circuit. It acts as a bridge just as the starter solenoid does. If you were to take a solenoid apart you'd see the bridge similarity.

Perhaps the contacts need cleaning. Perhaps a solder joint within the switch came loose. Perhaps the connector or a wire within the connector is bad. Wear. loose springs. Corrosion. Do a visual on the contacts area then check continuity in the different switch positions then check voltage going in and voltage coming out for resistance/decreases.

[Rgconner]

Listen son, if you touch Dad's bike you are going to hurt yourself.

It's hot hot and will burn you like the stove, so don't do it. (Demonstration with a squirt bottle and hot exhaust pipes/engine)

That's all I had to teach my 5 year old about the ignition switch...

 

[PennyDreadfuls]

Listen son, if you touch Dad's bike you are going to hurt yourself.

It's hot hot and will burn you like the stove, so don't do it. (Demonstration with a squirt bottle and hot exhaust pipes/engine)

That's all I had to teach my 5 year old about the ignition switch...

 

ha. well played.

[PennyDreadfuls]

FIXED   
I ended up pulling the ignition switch off and looked more carefully at the connections on bottom. The brown wire has a small 1/8" jump wire from one solder point to another solder point, then, the main brown wire comes off that solder point and heads towards the back of the bike. Not noticeable until the wire was pulled a bit but it was at the jump off point that the wire was split and separated away from the solder junction. A ugly solder job and the tail light is back on!