Back light

No!!  Theres 2 wires inside the bulb!! One for clear bright Brake light and one for Running light.. this running light works intermittently!!

Ignition ON. Headlight works and back light is off !! Brake light works very well. If I start the bike and go for a ride, the back light will be illuminated like our cars and shut off at any moment and come back (little bright, not the same bright as my brake one)(thats what Im talking about 2 wires inside the same 💡) Hihi 😉 

3 wires go to the tail light.
Tail light live. 
Brake light live. 
Common earth for both tail and brake lights. 
If your tail light intermittently illuminates with the lights switch in the off position it must be picking up a live feed from somewhere where it shouldn't. 
Disconnect one of the two live wires, test which is disconnected by applying the brake. If it still illuminates then you have disconnected the live for the tail light. If it doesn't illuminate reconnect and disconnect the other. Then you'll need to trace that wire back to try to find where it's picking up a live feed that it shouldn't be. 

Is it supposed to illuminate ignition ON without running engine? I guess ..

Maxbou92 wrote:

Is it supposed to illuminate ignition ON without running engine? I guess ..

As long as the right handlebar switch is in the "PO" or "On" position

US and EURO bikes have different lights switch gear. 
Euro = off : po : on. 
US = off : on. 
As you've got US I won't list the EURO info. 

Ignition off = all lights off including brake light switches. 

Ignition on/light switch off = front running light on, back running light off. Front and back brake light dwitches operational independantly of each other. 

Ignition on/light switch on = front head light on, tail light on. Front and back brake lights operational independently of each other. 
When light switch is on obviously the high low beam switch is also operational. 

All the above regardless of the engine running or not. It makes no difference. 

So if anything is happening differently to the above you've a wiring or switch fault. 

 

Mmmm okay!!! Its been a few hours that I test my wires.. Ive found brake light switch and of course there’s current .. but the other one (running light) goes through the headlights. So I test each one (red one) and they all have current!!! I already strip all the main and check each wires !!!

Warren3200gt wrote:

US and EURO bikes have different lights switch gear. 
Euro = off : po : on. 
US = off : on. 





 

I am pretty sure the off/on feature disappeared from US bikes in 1975, as that is the year that the Federal Government mandated that motorcycle headlights must come on when the engine is started and must remain illuminated while operated on public roads. The op says his is a 1980 model, so if it has the stock switch gear, there will not be an on/off feature.
 

. The red wire was cut near the fuel tank!! Now I have curent in  the rear plug. But no running light!!! Only brake light (blue one)

TexasKZ wrote:

Warren3200gt wrote:

US and EURO bikes have different lights switch gear. 
Euro = off : po : on. 
US = off : on. 








 

I am pretty sure the off/on feature disappeared from US bikes in 1975,



 

Nope, I have a US 77 650 which is just on/off.
I actually changed the sealed beam to a bulb bowl and wired the side light up to be permanently on ignition switched. 

Interesting.I wonder if there was an extended compliance period?

By the way Maxbou92, what was under that wad of electrical tape on the red wire?