Topic: CB400F Front LED maker lights dim when they should be off.

[Alaxy Galaxy]

I'm trying to sort out a minor issue that's been bugging me:

I replaced my idiot lights and front maker lights with LED bulbs and I installed a headlight on-off switch (not a relay, but a ground interrupt switch).

I have an OEM sealed-beam headlight, and if I I turn it off in the lowbeam position, the marker lights stay on as they should. If I turn the headlight off in highbeam position, the markers light up dimly instead of staying off.

Furthermore, whenever I turn the headlight off, the blue idiot LED comes on no matter if I'm in Hi or Lo beam.

I'm scratching my head at this because I just can't see where residual current would come from if not by induction. There's really nothing complicated to these wiring diagrams at all, but it sure has me stumped!

[Alaxy Galaxy]

I've made a wiring diagram of the section in question. My added switch is in red.

[mattsz]

Weird.  How's your Hi/Lo switch?  All power to the blue indicator light and the running lights relies on that switch; maybe there's some low-level short between Hi and Lo positions providing enough current to illuminate your LEDs, but which wouldn't illuminate high-draw incandescent bulbs?

[Tomshep]

Yes, that is it. the current is going through both headlight filaments to the high beam LED which needs very little current to illuminate.
Place the red switch on and it will not happen because the current is shunted to ground. There is an error in the marker wiring but it looks  like a typo. "Turn right" and "turn left" are transposed after the low/high switch left hand pole.  Break the line between the fuse and the right hand pole of the high/ low switch that goes to the bulb and put the off switch there instead. Reinstate the connection to ground.

[Alaxy Galaxy]

Yes, that is it. the current is going through both headlight filaments to the high beam LED which needs very little current to illuminate.
Place the red switch in series with the fuse instead.

Oh. I hadn't thought of that but it makes perfect sense, at least for the idiot light. I could fix that bug by putting a high-current diode in series with the Hi-beam. Putting the switch in series with the fuse always kills the marker lights, which isn't as versatile as the setup I've devised.

Thanks for the tip!

[Tomshep]

I edited, having had another look. Read what I wrote because you are nearly there and need no diodes. If you break the feed where I suggest, you will keep the functionality of the marker lights.

[mattsz]

Break the line between the fuse and the right hand pole of the high/ low switch that goes to the bulb and put the off switch there instead...

Makes sense on paper, but how would you do that?  Isn't it all internal switch contacts?

[Alaxy Galaxy]

Break the line between the fuse and the right hand pole of the high/ low switch that goes to the bulb and put the off switch there instead...

Makes sense on paper, but how would you do that?  Isn't it all internal switch contacts?

Unfortunately, it is. In all fairness, this is a minor issue. I don't mind having the marker lights slightly dim; it's just that I'm curious as to why they are like that.

[mattsz]

Unfortunately, it is. In all fairness, this is a minor issue. I don't mind having the marker lights slightly dim; it's just that I'm curious as to why they are like that.

Yeah... weird.  My previous post might explain both of your symptoms...

[Tomshep]

t$he connection to the switch in the earth line is not quite right. To work properly, the high beam warning lamp must be grounded to the bulb common, the input to the grounding switch, if you like, not the frame ground. Now the marker lights will always be on when dip is selected and off while main is selected. The headlamp will be on if the ground switch is on but the high beam warning lamp will only be on if the high beam and ground switch are both on.

[mattsz]

t$he connection to the switch in the earth line is not quite right. To work properly, the high beam warning lamp must be grounded to the bulb common, the input to the grounding switch, if you like, not the frame ground. Now the marker lights will always be on when dip is selected and off while main is selected. The headlamp will be on if the ground switch is on but the high beam warning lamp will only be on if the high beam and ground switch are both on.

Why not connect the hi beam warning light to the frame ground?

If "dip" means "lo beam," and "main" means "hi beam," then what you've described is how they're meant to function... isn't it?

[Tomshep]

Because it doesn't work properly connected to frame ground. The led will be on all the time, main or dip and can indicate main beam when the headlamp is switched off. I am glad that you followed the functional description. It is indeed an explanation of the correct operation.

[mattsz]

Because it doesn't work properly connected to frame ground. The led will be on all the time, main or dip and can indicate main beam when the headlamp is switched off.

Sorry, but...

I can see how his current setup would cause the blue LED "Hi" indicator to light when his headlight is off and his Hi/Lo switch is set to "Hi."  But the LED should not light in "dip" position, regardless of its path to ground... if everything else is working correctly.  Where is it getting power from in "dip" position?

Something must be amiss other than his ground interrupt switch; otherwise, if his Hi/Lo switch is set to "Lo," then the blue indicator should not be getting any current at all, regardless of its path to ground.  Yet it appears to be.

Same with the running lights, which should be operating independently of his ground interrupt switch - if the Hi/Lo switch is set to "Hi," then the running lights should not be getting any current at all.  Yet they appear to be.

[Alaxy Galaxy]

Because it doesn't work properly connected to frame ground. The led will be on all the time, main or dip and can indicate main beam when the headlamp is switched off.

Sorry, but...

I can see how his current setup would cause the blue LED "Hi" indicator to light when his headlight is off and his Hi/Lo switch is set to "Hi."  But the LED should not light in "dip" position, regardless of its path to ground... if everything else is working correctly.  Where is it getting power from in "dip" position?

Something must be amiss other than his ground interrupt switch; otherwise, if his Hi/Lo switch is set to "Lo," then the blue indicator should not be getting any current at all, regardless of its path to ground.  Yet it appears to be.

Same with the running lights, which should be operating independently of his ground interrupt switch - if the Hi/Lo switch is set to "Hi," then the running lights should not be getting any current at all.  Yet they appear to be.

Mattsz, you are correct in your description. If I ground the headlight, the blue indicator works like it should, which makes sense with the diagram. Furthermore, when I lift the ground and kill the headlight, it makes absolute sense to me now that the blue lamp stays on no matter what. I'm limited as to what I can interrupt with that switch, because the switching system isn't as accessible as my diagram makes it seem. Most of it consists of interconnections within the handlebar controls.

I'm still baffled by the marker lights, though. 

[mattsz]

Yeah - if I were me, I'd probably dip (sorry!) into the wiring harness switch connectors and start testing switch functionality and light wiring...

[Alaxy Galaxy]

Yeah - if I were me, I'd probably dip (sorry!) into the wiring harness switch connectors and start testing switch functionality and light wiring...

I did. And here's what I came up with, and it finally makes sense. Maybe I could put a shunt resistor across my on-off switch. But then it'd always draw current and might not save on available power compared to the 3 LEDs being lit anyway.

[mattsz]

Yeah - if I were me, I'd probably dip (sorry!) into the wiring harness switch connectors and start testing switch functionality and light wiring...

I did. And here's what I came up with, and it finally makes sense. Maybe I could put a shunt resistor across my on-off switch. But then it'd always draw current and might not save on available power compared to the 3 LEDs being lit anyway.

Ah.  Your new diagram looks the same, except for how you've represented the Hi/Lo switch.  If that change is true representation of how the switch is configured, then I can see how the marker lights could get current through the headlight filaments when you open your ground interrupt switch.

Perhaps you could add some kind of diode between the headlight bulb and Hi/Lo switch which would prevent current from back-flowing through the low beam filament to the marker lights?

Or, simply change your right-hand switch module to the "UK" style which would provide you with the switchable headlight.  I understand it's a simple change.  Or if you want to stick with do-it-yourself, install your own switch to duplicate the OEM headlight switch's function.  Do you have a UK diagram?  It's differences are pretty clear...

[Alaxy Galaxy]

Ah.  Your new diagram looks the same, except for how you've represented the Hi/Lo switch.

I opened up a spare LH module and this is a better representation of the system.

Perhaps you could add some kind of diode between the headlight bulb and Hi/Lo switch which would prevent current from back-flowing through the low beam filament to the marker lights?

Or, simply change your right-hand switch module to the "UK" style which would provide you with the switchable headlight.  I understand it's a simple change.  Or if you want to stick with do-it-yourself, install your own switch to duplicate the OEM headlight switch's function.  Do you have a UK diagram?  It's differences are pretty clear...

From What I can see, the UK bikes don't have marker lights, am I correct? And the headlight switch basically cascades the fuses (no lights, only the taillight or all lights). This might be an option.

By my calculations, if I start putting diodes inline with the HL filaments, I'd have to have 5A diode for the 50W Hibeam. It seems like a lot. I may try a resistor like I said, or just leave it as is. I'm a sucker for "all the options" and I wanted to see if I could, with two switches, have all 4 lighting possibilities. Mostly, I put that switch there to kill the headlight while warmup.

[Tomshep]

Why not just put a double pole switch in series with the dip switch so you switch off both filament supplies simultaneously. That fixes the problem completely. Again, lose the earth side cutout.

[Alaxy Galaxy]

Why not just put a double pole switch in series with the dip switch so you switch off both filament supplies simultaneously. That fixes the problem completely. Again, lose the earth side cutout.

I might go that route, yeah. I'd put a DPST relay instead, as I'm really adamant with leaving the bike OEM-looking. With my newly added on-off switch (from a CB360), I have access to an SPST switch, independent from ground. So as long as I can find bullet connectors, I can insert a relay in there.

[Alaxy Galaxy]

I ended up using a 10A DPDT relay to switch both filaments. It all works fine now.

As it stands, the non-energized state has the headlamp off. Since I'll be doing most of my riding with the headlight on, I'd like for it to be the opposite. If I want to do that, however, I need to open up and change the contacts in the RH handlebar slide switch to close the contact in the "off" position.

Am I overthinking this?

[Tomshep]

Yes.
You have both normally open and normally closed contacts in the relay.
Just swap them over and the relay works in the opposite sense. It is the proper way to connect it as it will fail safe with the lights on.