Simple ignition switch problems with tail light.

[chrisbuckart]

Hello, I have recently swapped the stock ignition switch on my 1978 650 Special with a TC Bros simple three wire ignition switch. I thought this would just be a simple swap, but it's not been quite as simple as expected. I'm working with three wires, Brown( turn signals and headlamp fuse), Blue (tail light), and red (ignition). The back of the TC Bros switch has three points of connection labeled ST, B, and G. My first hurdle is not really knowing which wire goes where. I've not been able to find much info on this as well. So I began making connections and noting them, as well as what was working and not working when the ignition key was turned one click, then the second click. If I'm understanding how this new ignition switch is supposed to work, I believe one click turns on everything except ignition. And the second click allows me to start the bike. Long story short, I've wired the switch pretty much in every combination possible with the three wires and none of them are working as it should. I'm able to get power to everything (2 clicks)but the brake levers are not activating the brake light. But when I take it back to one click no power to anything but the brake levers activate the brake light. It's probably a simple fix, but I'm pretty in experienced with the electrical system and find the wiring diagrams difficult to read. Also the bike has a pamco ignition installed and I have removed all of the unnecessary little black boxes. It's been running great until I swapped the ignition switch. Any advise would be greatly appreciated. Thanks gang!

 

[chrisbuckart]

Also one more thing to note. When I do have power to everything the stock kill switch seems to be bypassed. I can have it on or off and still have power to the bike with the ignition switch set to 2 clicks.

 

[peanut]

first thing I would do in your place is contact TC Bros and ask them for a schematic of their switch. TC Bros have no business sending out an electrical item without some sort of instructions or wiring schematic. A wrong connection could potentially cause damage to wiring or components

If you have the original switch the likelihood is that the three wires connect in the same relative positions as the original switch. However having said that you should obtain a voltohm meter and check the switches

On your original Switch the park position for lights is extreme left of the steering lock position then going clockwise there is the steer lock position then the off position then the On position .

With the new switch it may not have a Park/standby position ? it probably doesn't have a steering lock either ??

The Red wire is the 12v+ supply from the battery to the ignition switch .(It comes via the Fuse block ) this needs to go to the common terminal on your new switch (probably B for battery ?)


The brown wire is the switched 12v+ supply out of the switch when you turn the ignition on second click . It supplies loads of stuff incl horn, headlight, stop light, tail light,flasher cancelling unit etc This cable should connect to the terminal that connects with the red cable terminal when the switch is put in the On position

The other wire should be a blue/yellow wire ,standby or park switch position (fully left ?) that feeds only the reserve lighting relay for parking lights. If you have a standby position on the new switch ( possibly extreme left ) it should connect there so that it connects with red cable terminal when the switch is at full anti-clockwise position

There is no blue wire connection on the ignition switch to the tail light. It should be Blue/yellow cable which feeds the Reserve Light relay which then feed the tail light on a blue cable

 

[chrisbuckart]

Peanut, awesome information! I appreciate you breaking it all down for me. I'll dig into this a bit more tonight when I get home from work.

Also yes, the the blue is actually a blue/yellow.