Weird headlight wiring question

[arotaryphone]

Hi everyone. I’m working on replacing my ‘95 K75’s headlight with a dual-H7 headlight off an F800. This seems wildly ambitious for someone of my level of expertise, but I’m learning a lot about ‘lectricals ‘n stuff in the process. I think I’ve mostly got the wiring figured out (how naive!), but my conundrum now is how to make the F800 headlight operate as designed on the K75’s lighting system. The goal is for the high-beam bulb to illuminate in addition to the low-beam when turned on. I understand that on earlier K75 models, there was a “white wire” in the relay box that caused the high and low-beam of the H4 to turn on simultaneously. I think I would want this for what I’m trying to do, right? I don’t see that wire in my later-model ‘95. Is it something I could add somehow? I can’t seem to find a picture of what that wire looks like or a diagram of how it’s connected. Can anyone shed some light? Thanks!

(Additional details: My bike has the beefier alternator and I am installing a headlight relay kit from Eastern Beaver)

[rbm]

Maybe your best bet is to do some custom wiring with your Eastern Beaver kit (if possible):
- feed Green/Blue from Pin 8 on the Lefthand switch cluster to the low beam H7
- feed White from Pin 1 on the Lefthand switch cluster to the High beam H7

Power from Green/Blue will run the the Low beam H7 at all times and will respond to the load shed relay.  The High beam H7 will come on with either the Flash mode or the High beam mode.  Separate grounds need to be run from each lamp to the grounding point under the tank.  Check the current draw of the entire system and determine if the EB supply wire is heavy enough gauge to handle the expected current for both lamps.

I drew up a schematic and posted it below.

BTW, which Eastern Beaver kit did you get?  Also, is your K75 fitted with a North American righthand switch cluster without a light switch or a European righthand switch cluster with a light switch?

[arotaryphone]

Thanks so much for responding! My EB relay is an H4 conversion kit. I’ll attach a picture of it. Looks like I have the standard NA controls.

[Scott_]

I'd suggest adding a larger ground wire(the brown one).
The stock wire harness and even the relay setup you have, were designed around the concept of only 1 element of the lamp being energized at a time-- not both.
The last thing you want to do is to melt your wiring from overload.

[rbm]

@arotaryphone: Any circuit I propose is making the assumption that the low beam H7 will be on at all times that the ignition is on.  Is there a requirement that you be able to turn on and off the low beam?  If that is a requirement, then you'll have to replace the righthand North American switch cluster with a European switch cluster.

Scott_ has a very valid point.  It's best to run separate 1.5mm² ground wires from each H7 to the main ground connection point under the tank.  Ignore the ground provided on the EB really kit.

[Laitch]

On EB's Non H4 page—which covers the bulb type conversion you're using—you would have found this dual beam option kit. You could still order it.


 

[arotaryphone]

@arotaryphone: Any circuit I propose is making the assumption that the low beam H7 will be on at all times that the ignition is on.  Is there a requirement that you be able to turn on and off the low beam?  If that is a requirement, then you'll have to replace the righthand North American switch cluster with a European switch cluster.

Scott_ has a very valid point.  It's best to run separate 1.5mm² ground wires from each H7 to the main ground connection point under the tank.  Ignore the ground provided on the EB really kit.

I think having the low beam on while the bike is running would be fine. I can’t think of a situation where I would need to turn it off.

This might be a silly question, but I believe my relay connects directly to the battery. Is it still better to run a separate ground in my case? I do intend to check and clean the grounding points since I already have the tank off to replace the old fuel lines, so it wouldn’t be much too much trouble to do.

[arotaryphone]

On EB's Non H4 page—which covers the bulb type conversion you're using—you would have found this dual beam option kit. You could still order it.

I believe that’s the exact one I have! Glad to have some confirmation that I picked the right one

[rbm]

Posted the schematic above and updated the description.

[arotaryphone]

Thanks Robert! However... I think I may have discovered another wrinkle now that I’ve got the headlight assembly back on the bench. I think the two H7 bulbs and the parking light bulb all share one ground connection that comes out of the central connector on the headlight assembly. Multimeter says there’s continuity between the ground wires on the two bulb connectors. Through trial and error, I’ve figured out what the other pins in the central connector go to. It’s not as pretty as yours, but I made a diagram of the pins. Does this make things a lot more complicated?

[rbm]

That's ok so long as the gauge of wire you choose to connect the ground to the bike's frame is sufficient to handle the current that will be drawn by all bulbs when operating.  Current is calculated from Ohms law - I=P/V  where P is power in watts for both bulbs and V is the applied battery voltage.  Use a wire gauge table to determine the correct wire. BTW, all along in this conversation, we've made the assumption that your bulbs are halogens and not LEDs.  You probably should size your wiring for maximum load of halogens even if you are using LEDs, because you never know in the future whether another owner will change the bulbs.

So

• Ground will be a Brown wire to frame ground under the tank, probably 1.5mm² (that's large enough to carry 15A over the distance you'll need.  With 55/60 H7 halogen bulbs, your current draw is about 9.5A, so you have good margin)
• Parking will go to Grey/White
• Lo will go to Yellow off your EB relay kit
• Hi will go to White off your EB relay kit

[Scott_]

.......because you never know in the future whether another owner will change the bulbs.

That's exactly what I did with my 'R' bike when I purchased it. The P.O. had installed an H4 LED, but when I installed my modulator(from previous bike), the LED's were so fast to extinguish light, they actually pulsed on/off with the modulator.... and that's illegal for non-LEO/ambulance applications.
So I went and installed a standard halogen H4 lamp and all is good, not to mention the projected light pattern is what it should be as well.

[arotaryphone]

You guys are the best! I’m finally starting to see the light at the end of the tunnel on this project.

I should have specified that I am running halogens for the headlight. Front turn signals will be LEDs with resistors. They seemed to flash at the normal rate when I tested them on the bike last fall.

I’ll draw up another caveman-level diagram to check that I have everything straight and post it here tonight.

P.S.- I have some 16 AWG marine wire, which seems to be equivalent to the 1.5mm² metric size. It’s all yellow though, so I may pick up some more in the appropriate colors.

[The Mighty Gryphon]

16AWG marine wire is great.  You could probably even use 18AWG.  When you figure that the distance from the headlight to the ground connection under the tank is less than 1m, the voltage drop/power dissipation requirement is so low that almost any wire size greater than 22AWG will work.  I never measured it, but the factory wiring seems to be around 18AWG. 

IMO, with the length of the wires on the bike, the main consideration in selecting a wire size is the mechanical strength of the wire and not the resistance. 

[rbm]

Wire gauge is important because it determines the maximum current carrying capacity.  The minimum gauge that should be used in this application is 16GA even if the run is 1 metre or so. Larger wire like 14GA could also be used but I wouldn't go as low as 18GA.

[arotaryphone]

Hiya, folks. Apologies for not following up yet, between work and some other life stuff I haven't had a lot of time to work on my bike. Now my goal is to try to get it done before winter sets in.

Maybe your best bet is to do some custom wiring with your Eastern Beaver kit (if possible):
- feed Green/Blue from Pin 8 on the Lefthand switch cluster to the low beam H7
- feed White from Pin 1 on the Lefthand switch cluster to the High beam H7

Power from Green/Blue will run the the Low beam H7 at all times and will respond to the load shed relay.  The High beam H7 will come on with either the Flash mode or the High beam mode.  Separate grounds need to be run from each lamp to the grounding point under the tank.  Check the current draw of the entire system and determine if the EB supply wire is heavy enough gauge to handle the expected current for both lamps.

I drew up a schematic and posted it below.

BTW, which Eastern Beaver kit did you get?  Also, is your K75 fitted with a North American righthand switch cluster without a light switch or a European righthand switch cluster with a light switch?

This might be a dumb question, but what's the appropriate place to connect to the green/blue wire? I've found it in the left-side handlebar connector under the tank, but I'm scratching my head a bit on how to connect to it. Am I splicing off it, or connecting to the end of it somewhere?

[rbm]

I want to change my mind as to how you should be connecting up you EB relay kit to the left hand switch.  I was too quick to make the schematic for you and I introduced an error.  Don't use the Blue/Green wire as I originally drew.

You should pick up the low beam signal for your EB kit from the solid yellow wire and the signal for you high beam from the solid white wire.  These are best obtained from the H4 headlight connector itself at the front of the bike.  Use a male H4 connector to make your connection.

[arotaryphone]

Roger that. My EB kit has an H4 plug that will connect just like that. Will the low beam still stay on when the high beam is turned on?

[rbm]

No.  One or the other.  They are fed from the same power source and the wiper of the switch moves from one contact to the other.  Expect your low beam to extinguish and your high beam to illuminate.

If you want low beam to stay on while also allowing high beam to illuminate (using your current EB relay kit), then pick up low beam trigger from White/Yellow.  That will require you to splice into existing wiring because you can't pick it up from the H4 socket.  What you will end up with is daylight running lights (DRL) for the low beam.  Low beam will come on with the ignition (I don't know if you have a USA or European right hand switch cluster).

[arotaryphone]

No.  One or the other.  They are fed from the same power source and the wiper of the switch moves from one contact to the other.  Expect your low beam to extinguish and your high beam to illuminate.

If you want low beam to stay on while also allowing high beam to illuminate (using your current EB relay kit), then pick up low beam trigger from White/Yellow.  That will require you to splice into existing wiring because you can't pick it up from the H4 socket.  What you will end up with is daylight running lights (DRL) for the low beam.  Low beam will come on with the ignition (I don't know if you have a USA or European right hand switch cluster).

Gotcha... it's been a while since I've started up the bike, does it not normally turn on the headlight with ignition? Also, does it matter much where I splice into the White/Yellow wire?

P.S.-  I've got a US right hand cluster

[frankenduck]

You should pick up the low beam signal for your EB kit from the solid yellow wire and the signal for you high beam from the solid white wire.  These are best obtained from the H4 headlight connector itself at the front of the bike.  Use a male H4 connector to make your connection.

Six of one or half dozen of the other but I always tap my headlight relay trigger wires into the solid yellow/white wires on the bike side of the left combo switch connector. I use Posi-Taps to do this.

[arotaryphone]

Six of one or half dozen of the other but I always tap my headlight relay trigger wires into the solid yellow/white wires on the bike side of the left combo switch connector. I use Posi-Taps to do this.

I'm using Posi-locks and Posi-taps for all my electrical tampering 

[Laitch]

I always tap my headlight relay trigger wires into the solid yellow/white wires on the bike side of the left combo switch connector.

What is the side opposite the bike side—the car side, the bicycle side, the bathroom side? I just can't picture it. 

[frankenduck]

What is the side opposite the bike side—the car side, the bicycle side, the bathroom side? I just can't picture it. 

There's two sides to the connector: The "bike side" which is the side that is part of the bike's main wiring harness and the "switch side" that's part of the switch assembly.  I connect to the "bike side" because it makes life easier if the left combo switch ever needs to be replaced.

[arotaryphone]

Let’s see if I’ve got this straight… I tap into this White/Yellow wire in the left handlebar connector (bike-side ). That goes to the yellow signal wire on my relay. Solid white high beam wire (from H4 connector or tapped from further back) goes to solid white signal wire on the relay. Low beam is always on, stays on when the high beam is on, and my left-hand switches still work in a way that makes sense?