Wire a 3rd brake light?
- Thread starter wtf33
- Start date
Ohmster
Kansas Motorcycle Works
Are you planning on having the 3rd light be the only tail and brake light or are you wanting to add in a 3rd to work with your existing 2 rear brake and tail lights that you have?
If you want to have the 3rd or a center only brake and tail and make your existing 2 lights be turn signal then do this. At the front of your rear fender there will be your rear fender connector. It is a small gray rectangle connector. There are 6 wires in that connector. 2 red wires, one brown wire, one purple wire and 2 black wires. You can try to depin the 2 red wires or you can cut them flush at the connector. This is your tail and brake light. You can splice those to a new red wire and route that back to your new 3rd light at the rear. I would also pick up a chassis ground spot on the frame in the battery tray area and run a new ground wire along with the new red wire. Cover with heat shrink for wear protection and terminate it to your new light and your good to go.
If you want the new light to work with your existing 2 lights as a brake and tail light then do the exact thing except instead of cutting the red wires out of the harness and splicing into them, cut them and splice in a new red wire that is spliced back into the rear fender harness so this brake and tail light output is running in parallel with the 2 existing brake and tail light outputs. Add in a new chassis ground wire and now you have 3 lights on the rear of the bike working as a brake and tail light.
Hope this helps. If you have any problems or questions feel free to send me a pm.
If you want to have the 3rd or a center only brake and tail and make your existing 2 lights be turn signal then do this. At the front of your rear fender there will be your rear fender connector. It is a small gray rectangle connector. There are 6 wires in that connector. 2 red wires, one brown wire, one purple wire and 2 black wires. You can try to depin the 2 red wires or you can cut them flush at the connector. This is your tail and brake light. You can splice those to a new red wire and route that back to your new 3rd light at the rear. I would also pick up a chassis ground spot on the frame in the battery tray area and run a new ground wire along with the new red wire. Cover with heat shrink for wear protection and terminate it to your new light and your good to go.
If you want the new light to work with your existing 2 lights as a brake and tail light then do the exact thing except instead of cutting the red wires out of the harness and splicing into them, cut them and splice in a new red wire that is spliced back into the rear fender harness so this brake and tail light output is running in parallel with the 2 existing brake and tail light outputs. Add in a new chassis ground wire and now you have 3 lights on the rear of the bike working as a brake and tail light.
Hope this helps. If you have any problems or questions feel free to send me a pm.
KaptinAmerika
Guru
So what is the max amp load on that circuit for the ehc?
KaptinAmerika
Guru
Don't the brake and turn signal power come from the same wire with the EHC determining whether it is acting as a blinker or brake at the current moment?
Also, does the same FET serve tail and turn/brake or do they each have their own independent FET?
Also, does the same FET serve tail and turn/brake or do they each have their own independent FET?
Ohmster
Kansas Motorcycle Works
The turn signal is on a separate output so you can isolate the turn from the brake and tail output. The reason you would need to splice both the red wire brake outputs together to the new 3rd light is that exact reason you stated. The EHC will determine if say the right turn is activated and brake is applied then the right side would flash while the left would stay on constant. By splicing both brake outputs together in parallel a constant 12vdc would be applied to the brake light by one of the two outputs. The other brake output would flash 12vdc on and off but the other output would override the flashing output since a constant 12vdc would be applied as long as brake is applied. If no brake is applied and only a turn signal is activated then only the turn signal output activated would flash 12vdc to the activated marker.
Hope that helps.
Jason
Hope that helps.
Jason
wtf33
New Member
Jason, thank you for your quick reply regarding my lighting question. However I have to agree with Curtis about the actual circuitry because my service manual and test I made with my multimeter verify the red conductor as a key on constant hot and the brown and purple conductors performing the turn/brake light duties. This presents my problem of not being able to lite a 3rd light because it would either flash when a turn is called for when using only one side of the bikes circuitry and using both would short both turn signals together and that is out of the question. I have found away to control a 3rd light (brake only ) using 2 relays to open/close a ground and a +12v using the brown and purple turn/brake circuits as switch legs to fire the 2 relays but then the new light would'nt have any tail function which I want since my main objective is to allow more visibility to the folks behind me who are pre-occupied with other important issues besides watching out for those of us on bikes! If you know anything about how the stock LED lamps use 2 separate 12 volt sources to make the lamps burn dim with the tail circuit and bright from both im all ears. Appreciate you folks taking time to help...Kevin
Ohmster
Kansas Motorcycle Works
I stand corrected. Curtis and you are both right. Total brain fart there. The red is constant running lights and the brown and purple share the same function with the turn and brake. Different fet outputs on the board but same function.
So to do what you want to do becomes a bit trickier. One way to do it is to isolate your brake system from your EHC through a relay as you suggested. To do that you would need to tie both the front and rear brake inputs to the EHC together as the ground input to a relay.
The downside to that is under a long stop you will loose your turn signal staying on while you have brake applied. The EHC will no longer "see" a brake input and activate the self cancel feature.
Sorry for the confusion. I'll try better next time
So to do what you want to do becomes a bit trickier. One way to do it is to isolate your brake system from your EHC through a relay as you suggested. To do that you would need to tie both the front and rear brake inputs to the EHC together as the ground input to a relay.
The downside to that is under a long stop you will loose your turn signal staying on while you have brake applied. The EHC will no longer "see" a brake input and activate the self cancel feature.
Sorry for the confusion. I'll try better next time
KaptinAmerika
Guru
The only way I have come up with is through the use of a microcontroller.
I have a "guy" working on it but he is a bit flaky and hard to pin down.
I'm supposed to go see him today about it.
He claims he is done with it and just needs to get quotes for me.
We will see.
I have a "guy" working on it but he is a bit flaky and hard to pin down.
I'm supposed to go see him today about it.
He claims he is done with it and just needs to get quotes for me.
We will see.
wtf33
New Member
Hey Jason it sounds like you have dealt alot with these ECMs and Curtis if your contact comes through I'm ready to purchase his controller if you feel he has a unit that will do the job. I know you will be able to determine whether what he has is right because of the experience you have from being around bikes speaks for itself. Again much thanks to both of you taking time to help. Talk again soon ...
KaptinAmerika
Guru
He is actually building it to my specs and requirements.
I spoke with him today and he promised me the proto Friday.
Soon as I finish testing it then we will get manufacturing involved and I should have a release date.
I spoke with him today and he promised me the proto Friday.
Soon as I finish testing it then we will get manufacturing involved and I should have a release date.
