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High beam failure, 2018 NC750x

Vinny

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My high beam has failed on the 750X.. but to be honest, I tapped into the 5v wire in the back of the connector. I was needing a trigger to run some auxiliary lights when the high beam was switched on. I had isolated the light through a relay and didn't think the coil draw would be enough (on a micro relay) to do any harm. Well obviously it did because the high beam no longer works and not getting the blue high beam indicator on the dash panel.
So the big question is... Where does the 5V in the back of the headlight plug originate? There is 12v fed to headlight... is the 5v just power the dash indicator from a voltage divider network in the headlight itself, or is the 5v generated from the regulator and sent to the headlight? Obviously I don't have a manual so I'm asking here.

Thanks
 
As best I can tell from the 2018's wiring diagram, the 5V+ is generated in the LED headlight module itself. The module has 5 wires:
  1. Labeled "Po/L (BAT in)", a black wire that goes to a junction box where a number of 12V+ wires are interconnected. It looks like a number of these wires are hot when the ignition switch is closed - I reckon that this wire turns the LED headlight module on when the ignition switch is closed.
  2. Labeled "METER IND", a black/red wire that runs to an instrument panel connection labeled "HI BEAM". There's no indication of the voltage or source/sink of power in this wire. I reckon this wire is used to turn the hi beam indicator in the panel off and on and it's possible that this wire is 5V+ OR 12V+ on high beam only - but that's just a guess
  3. Labeled "DIMMER SW", a black/blue wire that runs to the common terminal of the dimmer switch, which is SPDT. (Note: this wire changes from black/blue to blue/white on its way to the switch, so you'll see blue/white at the switch terminal.) The switch terminal for the Low Beam position is open and the terminal for the High Beam position goes to ground. I think the mode of operation here is that this wire is normally 5V+, and the low beam is on, but when the dimmer switch grounds this wire (i.e. wire voltage = 0V), then the headlight module switches to hi beam. The blue wire that goes to the auxiliary connector tees off of this wire and it mimics the 5V+ on low beam. FWIW, I've been using this blue auxiliary wire to control my auxiliary lights thru a solid state timer relay for over year now without any problem (check this thread for the gory details: https://www.nc700-forum.com/threads/auxiliary-lighting-for-2018-nc750x.16641/)
  4. Labeled "H/L (BAT in)", a black/white wire that connects to Fuse #8 - I think this wire provides 12V+ power to the LED headlight module
  5. Labeled "GND", a black/green wire that connects to ground - which has gotta be the power return ground wire for the LED headlight module.
Now, none of this will necessarily solve your problem but it's all I got, except maybe to suggest checking your fuse? Or is it only the hi beam that's off?? And also to note that it seems to be normal operation for the blue/black & blue aux line to be grounded when the high beam is on so I'd guess that running it thru a relay coil shouldn't be the cause of your problem. It certainly works for me.
 
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As best I can tell from the 2018's wiring diagram, the 5V+ is generated in the LED headlight module itself. The module has 5 wires:
  1. Labeled "Po/L (BAT in)", a black wire that goes to a junction box where a number of 12V+ wires are interconnected. It looks like a number of these wires are hot when the ignition switch is closed - I reckon that this wire turns the LED headlight module on when the ignition switch is closed.
  2. Labeled "METER IND", a black/red wire that runs to an instrument panel connection labeled "HI BEAM". There's no indication of the voltage or source/sink of power in this wire. I reckon this wire is used to turn the hi beam indicator in the panel off and on and it's possible that this wire is 5V+ OR 12V+ on high beam only - but that's just a guess
  3. Labeled "DIMMER SW", a black/blue wire that runs to the common terminal of the dimmer switch, which is SPDT. (Note: this wire changes from black/blue to blue/white on its way to the switch, so you'll see blue/white at the switch terminal.) The switch terminal for the Low Beam position is open and the terminal for the High Beam position goes to ground. I think the mode of operation here is that this wire is normally 5V+, and the low beam is on, but when the dimmer switch grounds this wire (i.e. wire voltage = 0V), then the headlight module switches to hi beam. The blue wire that goes to the auxiliary connector tees off of this wire and it mimics the 5V+ on low beam. FWIW, I've been using this blue auxiliary wire to control my auxiliary lights thru a solid state timer relay for over year now without any problem (check this thread for the gory details: https://www.nc700-forum.com/threads/auxiliary-lighting-for-2018-nc750x.16641/)
  4. Labeled "H/L (BAT in)", a black/white wire that connects to Fuse #8 - I think this wire provides 12V+ power to the LED headlight module
  5. Labeled "GND", a black/green wire that connects to ground - which has gotta be the power return ground wire for the LED headlight module.
Now, none of this will necessarily solve your problem but it's all I got, except maybe to suggest checking your fuse? Or is it only the hi beam that's off?? And also to note that it seems to be normal operation for the blue/black & blue aux line to be grounded when the high beam is on so I'd guess that running it thru a relay coil shouldn't be the cause of your problem. It certainly works for me.
Thanks a bunch, CapeMan... this information helps a lot!
 
Someone just recently posted a schematic here: https://www.nc700-forum.com/threads...lasters-p3-on-2015-nc750xa.11957/#post-224154

These wiring diagrams change regularly by year, model, and market, so I have no idea if it matches your 2018 NC750X.

It's nice to have diagrams but 670cc's caution is dead on right - a wiring diagram for 2015 and 2018 are different (for example, the LED headlights came to the US in the 2018 model year - some significant changes there!) For that matter, there are some differences in the US's DCT and standard tranny wiring diagrams - per the diagram, the headlight fuse for the "manual" ("pedal"?) tranny is fuse #8 but the same function's fuse is #10 on the DCT. Go figure!
 
It's nice to have diagrams but 670cc's caution is dead on right - a wiring diagram for 2015 and 2018 are different (for example, the LED headlights came to the US in the 2018 model year - some significant changes there!) For that matter, there are some differences in the US's DCT and standard tranny wiring diagrams - per the diagram, the headlight fuse for the "manual" ("pedal"?) tranny is fuse #8 but the same function's fuse is #10 on the DCT. Go figure!
The wiring diagram is of an earlier model with halogen headlights... but it still helps a little. I think the only thing that may have changed is the LED headlight assembly and some of the wiring associated.
 
The wiring diagram is of an earlier model with halogen headlights... but it still helps a little. I think the only thing that may have changed is the LED headlight assembly and some of the wiring associated.

BTW, please let us know what the problem/solution is.
 
Well... this befuddles me. Was out riding the bike a couple days ago and the high beam just decides to work again. Honestly... I had check all the connections, even checked the 5v supposedly coming out of the headlight assembly sending the signal to the dash to illuminate the indicator... and nothing. Now... boom, it works. This had been an issue for almost a year and now it works. I am very happy its working, because a new headlight assembly is almost $800.00, but I would rather know what the problem was.
 
My high beam has failed on the 750X.. but to be honest, I tapped into the 5v wire in the back of the connector. I was needing a trigger to run some auxiliary lights when the high beam was switched on. I had isolated the light through a relay and didn't think the coil draw would be enough (on a micro relay) to do any harm. Well obviously it did because the high beam no longer works and not getting the blue high beam indicator on the dash panel.
So the big question is... Where does the 5V in the back of the headlight plug originate? There is 12v fed to headlight... is the 5v just power the dash indicator from a voltage divider network in the headlight itself, or is the 5v generated from the regulator and sent to the headlight? Obviously I don't have a manual so I'm asking here.

Thanks

Which wire have you used to feed the relay? "METTER IND" or "DIMMER SW"? (as mentioned by Capeman in a previous post)

Have you installed the relay by yourself or have used a pre-made board ? I'm asking this because it is very important to use a resistor (series) and a diode (parallel) on connections of the relays coil . This will prevent over current draw and reverse current, respectively. The resistor may be optional in some cases.

Just curious because I'm about to install an acessory controlled by the dimmer switch.

Thank's
 
As best I can tell from the 2018's wiring diagram, the 5V+ is generated in the LED headlight module itself. The module has 5 wires:
  1. Labeled "Po/L (BAT in)", a black wire that goes to a junction box where a number of 12V+ wires are interconnected. It looks like a number of these wires are hot when the ignition switch is closed - I reckon that this wire turns the LED headlight module on when the ignition switch is closed.
  2. Labeled "METER IND", a black/red wire that runs to an instrument panel connection labeled "HI BEAM". There's no indication of the voltage or source/sink of power in this wire. I reckon this wire is used to turn the hi beam indicator in the panel off and on and it's possible that this wire is 5V+ OR 12V+ on high beam only - but that's just a guess
  3. Labeled "DIMMER SW", a black/blue wire that runs to the common terminal of the dimmer switch, which is SPDT. (Note: this wire changes from black/blue to blue/white on its way to the switch, so you'll see blue/white at the switch terminal.) The switch terminal for the Low Beam position is open and the terminal for the High Beam position goes to ground. I think the mode of operation here is that this wire is normally 5V+, and the low beam is on, but when the dimmer switch grounds this wire (i.e. wire voltage = 0V), then the headlight module switches to hi beam. The blue wire that goes to the auxiliary connector tees off of this wire and it mimics the 5V+ on low beam. FWIW, I've been using this blue auxiliary wire to control my auxiliary lights thru a solid state timer relay for over year now without any problem (check this thread for the gory details: https://www.nc700-forum.com/threads/auxiliary-lighting-for-2018-nc750x.16641/)
  4. Labeled "H/L (BAT in)", a black/white wire that connects to Fuse #8 - I think this wire provides 12V+ power to the LED headlight module
  5. Labeled "GND", a black/green wire that connects to ground - which has gotta be the power return ground wire for the LED headlight module.
Now, none of this will necessarily solve your problem but it's all I got, except maybe to suggest checking your fuse? Or is it only the hi beam that's off?? And also to note that it seems to be normal operation for the blue/black & blue aux line to be grounded when the high beam is on so I'd guess that running it thru a relay coil shouldn't be the cause of your problem. It certainly works for me.
Thanks you Capeman for your insight, it did definitely help. So was installing my Denali D4 2.0 with dual intensity module a several months ago when I bought my NC. After hours trying to figure out where to find the high beam wire and failing everytime I was able to connected it with low intensity as running light. Yesterday I found this forum and you are talking about the black/ red wire that provide the high beam indicator in the dash. I found that my black/ red was cut above the separation of the harness, I fixed the wire and monitored the voltage and I got nothing. After thinking about it for couple minute I realized that I was totally stupid and forgot that it send the signal once the high beam is on. Reconnected the plug and got 10. something volts. That 10.5 ish volts was enough to trigger the relay to activate my high beam on my Denali. Do you can used the blue one to get you 12v and the black/ red one to trigger your high beam.
 
Thanks you Capeman for your insight, it did definitely help. So was installing my Denali D4 2.0 with dual intensity module a several months ago when I bought my NC. After hours trying to figure out where to find the high beam wire and failing everytime I was able to connected it with low intensity as running light. Yesterday I found this forum and you are talking about the black/ red wire that provide the high beam indicator in the dash. I found that my black/ red was cut above the separation of the harness, I fixed the wire and monitored the voltage and I got nothing. After thinking about it for couple minute I realized that I was totally stupid and forgot that it send the signal once the high beam is on. Reconnected the plug and got 10. something volts. That 10.5 ish volts was enough to trigger the relay to activate my high beam on my Denali. Do you can used the blue one to get you 12v and the black/ red one to trigger your high beam.


Yabut, you don't gotta mess around with wires to/from the instrument panel to do this. At the risk of repeating myself, please see https://www.nc700-forum.com/threads/auxiliary-lighting-for-2018-nc750x.16641/. If you follow these instructions, you'll get a good outcome .... I know 'cause that's exactly what I've done, and it works.





















'
 
Yabut, you don't gotta mess around with wires to/from the instrument panel to do this. At the risk of repeating myself, please see https://www.nc700-forum.com/threads/auxiliary-lighting-for-2018-nc750x.16641/. If you follow these instructions, you'll get a good outcome .... I know 'cause that's exactly what I've done, and it works.





















'
Don't worry it all been done IAW Denali installation instructions. I would have installed them without problem if the cable wasn't cutter. I didn't have any problem when they were installed on CB500X.
 
Hi guys, sorry for reviving this old thread, but could someone of you send me a photo of the original connector and the wiring? What I need is an exact pinout of the connector (which color goest to which pin in the connector). Thanks in advance.
 
I already figured it out by myself. Here is the pinout of the NC750x LED headlamp connector:
1680091974007.png

The image shows the back of the lamp and the connector placed there from the drivers point of view (bottom of the image is a bottom of the lamp). Black pins are N/C, the rest is as described on the picture. The DIMMER Switch pin works as mentioned in one of the above posts (when connected to GND switches to high beam)
 
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