Motorcycle Wiring Diagram for lighting

[jackietan]

I have a question for Motorcycle lighting. I have draft a wiring diagram posted here:
https://www.hdforums.com/forum/touring-models/1213320-harley-davidson-electra-glo.html

Electra Glo
Purple (Three LEDs lighted on the left) / Black & Green (Negative) / Purple & White (Three LEDs lighted on the right)



Existing light
Red (Brake) / White (Positive) / Green (Turn) / Black (Negative)

[jackietan]

1. Can I join both the Negative wire from Existing Light with the Electra Glo together?
2. Can I combine the two Electra Glo wires and connect to Existing Light Brake and Running separately?   
 

[jeroen79]

That would short the brake and running lights so they will always light together.
Add diodes before the join to keep the two lines separate.

[rbm]

Be careful.  I did a quick search on the Electra Glo brake light kit and it is supposed to be used with a provided module.  The module is supposed to adapt the lights to the existing HD wiring harness.  I am not a HD knowledgable person but I would think that the wiring on the HD is Canbus and not old-school.  So paralleling the Electra Glos onto the existing signal and brake circuits will most certainly upset the electronics on your bike and may do damage.  Have you tried to follow the provided installation instructions?