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Headlight Wiring

Discussion in 'The Garage' started by David Toll, Dec 29, 2019.

  1. David Toll

    David Toll Reliving my youth? Top Contributor

    As promised gents, I am currently engaged in connecting up the headlight wiring on my SE. I have poured over the relevant wiring diagrams and would like to say that they are beginning to make more sense but that would be untrue. The large blocks go together easily and only one way. Pic. 1 shows the turn signal earths hooked up to a double black. Pic. 2 shows the chocolate brown power wire from the new left hand short stalk indicators hooked up to a double chocolate brown. No, we are not colour blind! To add to the confusion, the power wire on Geoff's short stalk indicator is black. (Geoff's is the Aussie equivalent of Mikes).

    Pic. 3 shows the power wire from the right hand indicator hooked up to a dark green double. Both of the other wires in these doubles come from the left hand main harness. Pic. 4 shows the headlight connector attached to the harness. This is the old connector from my original headlight - seems better made than the Pommy replacement that came with the new lamp. I will fit the black to one of the spare locations on a double as, I assume, they are all earths. Pic 5 shows my dilemma. I have two blue wires coming down from the right hand switch. There doesn't appear to be a place for them. The double blue above them holds the tacho and speedo meter light connections as per the wiring diagram. The single blue below appears to come from the right side main harness. I am left with these two blues. The SE wiring diagram has the double with the meter lights hooked up but the wires from the switch don't appear 'til later, unless I'm reading the damn thing wrong.
    Should I reconfigure an end and join them together, (pointless I would imagine), or should I disconnect the single from the main harness, put one of the blue switch wires in that connection, fit the harness wire with a female bullet and join it to the other switch wire?

    The other issue I have is the way the new light is fitting into the ears. The final picture shows an angled gap where the ear rubber and the headlight damper meet. I would have thought that this mount would have sat flat but the ears seem to require this splayed look to accommodate the width of the headlight. The headlight is a quality original from Classic bikes in the UK so I assume it isn't too wide. Am I doing something wrong here?
    I trust all of my friends here on the Forum will enjoy their New Year celebrations, avoid excess and the ensuing New Year's Day personal recriminations and enjoy a safe and prosperous 2020.
     

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  2. 5twins

    5twins XS650 Guru Top Contributor

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    This may be difficult but I'm sure we can sort it out. First we'll need a bit more info on your bike. An SE would be a '78 model but where is yours from? Is it an Aussie home market bike, U.S. import, or possibly a "world" or Euro import? Wiring differed slightly between the models, especially concerning the lighting and light switch. Also, most of your wiring looks clean and new. What's been replaced? Right switch, whole harness? Those items may not match the originals exactly. For instance, a U.S. model right switch had one blue wire coming out of it, from the on-off switch to the instrument lights. The Euro model, however, had two blues (one blue split), one running, again, to the instrument lights but the other running to the ignition switch.

    The headlight on-off switch controlled the tail light too up to '77. In '78, that changed. The tail light was connected directly and only to the ignition switch and was now controlled by it. The '77 ignition switch only powered the tail light in the "Park" position. The '78 switch powers it in both the "Park" and "On" positions. So, your new right switch with two blues may be a good thing. It may give you the means to take back control over the tail light on-off function, moving it back to the headlight on-off switch. However, you may need to do a little mod inside your ignition switch, on the switch plate that all the wires connect to. But, we can get into that later. Answer the questions about your bike's heritage first.

    But, I will take a guess now as to the blue wire coming out of one of your main harness looms. It appears to have a double bullet and then another single bullet connector branching off that. I think that blue connects to a blue/black in the harness and runs back to your RLU. I would say you are correct to have the two instrument light blues connected into it, and I would guess the single bullet should get one of the blues from the headlight on-off switch.
     
    David Toll likes this.
  3. David Toll

    David Toll Reliving my youth? Top Contributor

    Hello 5T,
    You have certainly scuttled any ideas I had about this being easier than it looks.
    OK, mine is a 1978 SE. An American import in surprisingly good condition when I bought it, (Serial No. 2FO-103194). I have replaced the harness with an item from Mikes supposedly suited to this model. Having said that, I did have to change a block connector in the bucket from bullet type to blade to get it to hook up. Both handlebar switches are new from Geoff's here in Oz. Remember, Geoff's is the Australian Mike's. They are supposed to be direct replacements for the originals that "Fit: 1976-78 North American Models". The outer covering on the right hand switch main cable is a little short and the internal wires are exposed an inch or so before they enter the bucket so I don't think it was designed for the "Buckhorn" bars but it makes the connections well enough. There are definitely 2 blue wires coming out of this switch.
    I fitted a new ignition switch and rebuilt/re-chromed the original tail light. I also fitted Mike's short stalk indicators - the ones with the black power wire that I mention in the previous post and used the earth wires with the circular terminals from my old turn signal set. I intend to keep the points system in support of RG's statement that "thousands of these things are running reliably using that engineer designed system". I may sing a different tune if she leaves me on the side of the road outside Byron Bay at 2:00 in the morning. Too this end, I have installed new coils, condensers, points, brushes and advance springs. This bike has only run for a few minutes before I started to strip it down. There is no battery fitted although I do have 2 sitting on the garage shelf in various states of low charge.
    The blocks in the bucket all went together easily, (you really can't screw that up) and most of the coloured wires seemed to find a home with wires of matching colour, e.g. turn signals, meter lights, ignition, brake light and headlight. I have rewired on Leo's principle that "black is earth, always was, always will be" and plugged any black wire into one of the many double connections available in the bucket. This doesn't include the black power wires coming from the turn signals which are actually dark green and chocolate brown and are hooked up accordingly.
    Actually, I was congratulating myself on the effectiveness of my efforts and trying to cram the whole set up into the headlight bucket to fit the lens when I noticed the unattached blue wires from the switch. Being connected to the switch, I assume that it is essential to introduce these wires into the blue wire loom if I want the switch to work. I could run a lead with a double connector from the blue double giving me three females there and another from the single, giving the required total of 5 females and hook everything up but I am not sure which blue should go where. Appreciate your interest and assistance.
     
    Last edited: Dec 30, 2019
  4. 5twins

    5twins XS650 Guru Top Contributor

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    Since you're working with aftermarket replacement stuff, I think you'll need to do some blue wire tracing. I think you should also do some studying of more wiring diagrams near to your model, in particular the '77 diagram and the '78E Standard diagram. You'll want to look a bit deeper into the lighting circuit than just the headlight bucket connections. Acquaint yourself with how the headlight on-off switch wires in on the '77 model. Trace the headlight power path back to it's source on the various diagrams. To successfully wire yours, I think you're going to have to combine elements from a couple of the diagrams.

    Let's start with your new right switch from Geoff's. While he claims it's a direct replacement for '76 to '78 U.S. models, the actual '78 switch was a bit different. The wire colors may be the same but the connectors differed. You've also got that extra blue wire coming out of it that the original didn't have. As I mentioned earlier, that will probably turn out to be a good thing. I assume you'd like to wire this up so the headlight on-off switch works all the time and so that it also controls your tail light. So, here's how I'd do it .....

    Connect one of the blues from your new right switch as I mentioned above, to the single after the double on the blue coming out of the main harness. Run the other blue over to your ignition switch plug and connect it into the blue or blue/yellow coming out of it. This is following how the '77 is wired. This will send power to your tail light controlled by the headlight on-off switch. Now we'll get into the little mod you may have to make to your ignition switch .....

    As mentioned earlier, in '78 the tail light was connected to and controlled by just the ignition switch. The headlight on-off switch was no longer connected to it and no longer had any control over it. What we're going to do here is revert back to the '77 wiring scheme so it does. If you open up the bottom of your new ignition switch, this is probably what the switch plate will look like .....

    [​IMG]

    The blue is for the tail light, red is power in, and brown is power out. The two connector group at the bottom with red and blue is the "Park" position. The 3 connector group at the top with the additional brown is the "On" position. As wired, the tail light gets powered in both positions. You don't want that. You only want the key to power it in the "Park" position. So, just clip the short blue jumper wire between the "Park" and "On" positions out of there. Simple mod and now the key will only power the tail light in the "Park" position, headlight on-off switch will control it when the key is in the "On" position.
     
  5. 5twins

    5twins XS650 Guru Top Contributor

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    I should probably also explain a bit more about the function of the headlight on-off switch on the '78 U.S. models. It was the last year for the switch on the U.S. models and it was somewhat neutered. That was because it was also the first year for the auto-on headlight safety relay. As delivered, the headlight on-off switch in the right handlebar control would only function with the key on, motor not running. As soon as you started the bike, the auto-on safety relay would kick in and bypass the handlebar switch. The handlebar switch sent headlight power to the RLU on the blue/black wire when turned on. From there, it was directed to the hi/lo switch and on to the headlight. The auto-on headlight safety relay taps into this blue/black wire, feeding it power once the relay is tripped. So, that turns the headlight on even if the handlebar switch is off. Pretty silly set-up if you ask me, but luckily it's easy to "fix". To restore full functionality to the handlebar headlight on-off switch on the '78 model, so it works all the time, motor running or not, simply disconnect the blue/black wire coming out of the safety relay and running to the RLU .....

    [​IMG]

    Now the overriding bypass power from the safety relay will simply not reach the RLU anymore. The relay is no doubt still doing it's thing, getting tripped once the motor starts, but it's power out on the blue/black wire isn't going anywhere now.
     
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  6. David Toll

    David Toll Reliving my youth? Top Contributor

    My thanks for all this 5T, greatly appreciated. I will spend a couple of days locating and studying the relevant diagrams and attempting to relate them back to my set up. I have the original ignition switch which I will pull tp pieces and check out the internals before I attack my new one.
    Will post back here as I encounter problems, ( which, undoubtedly, I will).
    Cheers
     
  7. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    On The headlight ear misalignment. Looks Like your ear is bent ( SO typical)
    [​IMG]
    get some all thread 1/2" or 13mm (ish) is good but check the hole sizes. also nuts and washers.
    1976 XS650 restoration and rebuild, advice and help welcomed!
    [​IMG]

    Actually a longer piece passing through both ears works even better . Lets you work both sides and measure so the headlight is a good fit. Done this "many" times.
     
    Last edited: Jan 1, 2020
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  8. 5twins

    5twins XS650 Guru Top Contributor

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    Yes, a long enough length of all-thread to fit through both ears, double-nutted on each one, inside nuts spaced same width as the headlight bucket.
     
  9. David Toll

    David Toll Reliving my youth? Top Contributor

    Happy New Year Gary, (& 5T of course).
    Just had a close look at the headlight ears and they seem pretty straight. Indeed, to accommodate the width of the headlight, they seem to angle straight out from where they attach to the upper forks. It seems to me that the headlight is too wide. Hope the photos show this but there doesn't appear to be the deformation obvious in your example. Wonder if those Pommie bastards sold me a Triumph headlight by mistake, I believe they're slightly wider. It also has the Parking light addition on the lens. Leo and Fred gave different instructions as how to wire this up. Leo says earth the brown, (brown & white I assume) and add the blue, (light green?), to the blue loom after the key switch. Not sure what he means. Fred says hook it to the Tail Light. That's at the other end of the bloody bike. I've got blue wires coming out of my ears!! (My ears that is not the bikes). My God! This electrical stuff is a challenge. Back to the diagrams.
     

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  10. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    This one is bent that should be a straight line.
    headlight.JPG
    Typically the other side will curve like that on the bottom from the crash.
     
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  11. David Toll

    David Toll Reliving my youth? Top Contributor

    Yes, I can see that......now. Wish you guys lived next door! OK, dismantle and get some rod.
    And why can't the people who make these things pick a colour and stick to it???
     
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  12. David Toll

    David Toll Reliving my youth? Top Contributor

    Checking through all this wiring stuff carefully. Had a look at the internals of my old ignition switch and found it be be just as 5T described, (no surprise). Haven't had the courage to "clip" the blue wire on the new one yet but I'm working on it. Left the meter lights plugged into the double and put one of the switch wires in the single. That leaves me with a blue wire going into the right side harness and one coming from the switch - both bullet heads.

    5T, in post 5 above you mention that to restore functionality to the handle bar switch I simply disconnect the blue/black wire coming out of the safety relay. Your accompanying picture seems to show a blue/white wire disconnected. On inspection of my wiring, I have a blue/white wire but no blue/black. Is the blue/white wire the one I must disconnect and is it termed "blue/black" in auto-electrical parlance, (just for my future reference)? Ask me about the social conditions in ancient Sparta or the theological basis for the Trinity and I will fill in your afternoon but auto-electrics..... hopeless.

    Finally, Gary, I used the illustrated set up to straighten my handlebar ears. Set the internal nuts at 210mm, (about 101/2") which seems to be the headlight width at the mounting points, (including rubber dampers). Put it back together and they still show a little gap - reduced but not square. Might try it again with less space between the internal nuts to bring the ear tips in.
    Cheers
     

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  13. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    That all looks very clean and shiny! Great work.
    I think you will want to widen the space between the nuts to increase the "bend in" of the ears.
     
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  14. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Yeah... what Gary sez. Another way. I used a piece of wood to hold 'em spread and the allthread to bend 'em in.

    MVIMG_20180206_202712.jpg
     
  15. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    You'll get this!
    When I'm putting a front end together I normally spend quite a bit of time working on the ears, getting them straightened/rebent to the original shape before they even go on the fork tubes. wood blocks, big hammers vice, c-clamps various drifts, whatever it takes to massage them back into shape. Slow and steady shaping, without denting, creasing wins this game.
     
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  16. 5twins

    5twins XS650 Guru Top Contributor

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    Look closely at my pic, there is a blue/black wire there and that's the one that needs to be disconnected. Yes, there is also a blue/white wire but it remains connected. That runs to the solenoid and is for your start button.
     
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  17. David Toll

    David Toll Reliving my youth? Top Contributor

    Thanks Gary & Jim. Any encouragement is greatly appreciated. My family think I'm too old for motorcycles and should be spending my time on the golf course or playing bingo or trimming the roses.... hmmmm. I will try pressing them out wider first and if that fails, I'll use Jim's board technique. Trial and error heh? I'm good at that.
    5T, you're right, (no surprise), there is a blue/black. I have it connected to a blue from the harness and the blue/black below the connector was down behind the airbox so......... I will clip the short blue in the ignition and disconnect this blue/black. That still leaves me with two unconnected blues in the headlight. Had a look at the '77 diagram and the standard '78 but they both seem to have a single blue wire coming from the switch. Interestingly, my original switch had 2 blues. God! If only the labels had lasted the distance!
     

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  18. 5twins

    5twins XS650 Guru Top Contributor

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    Yes, the '77 and '78 Standard diagrams both show only one blue from the headlight on-off switch, but they connect up differently. Connect one of your two new blues to the ignition switch like the '77 diagram shows. Combined with clipping the short blue jumper wire in the switch, this will give on-off control of the tail light back to the headlight on-off switch. Connect your 2nd new blue like the '78 Standard diagram shows, to the instrument lights.
     
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  19. David Toll

    David Toll Reliving my youth? Top Contributor

    According to the '78 diagram, one of the blues I have coming from the switch should actually be LB and should run to the reserve lighting box. The other blue from the switch is the one connected behind the double in the headlight. Seeing as how they are the same colour in my setup, I'm not sure how to tell them apart. 5T suggests that one of these should be connected to the ignition switch, but which one? In the '77 diagram the blue from the tail light runs to the headlight bucket and joins at the double, (actually there are 4 wires connected here). In the '78 diagram the blue from the tail light runs to the light checker box but I can't see a blue from it running to the headlamp bucket and if it does, there is nowhere to connect it. You gentlemen are right, studying the diagram does help to clarify the layout but I am still a long way from comprehending it and, even with the blue wire to ignition link, I am one connector short.

    I am starting to think that my cycle has a straight '77 wiring set up. According to Skull, the model no. for this series began at 2FO-100101. Mine is 2FO-103194 - fairly early in the model run I would assume, seeing as how they went to 150000 units. Obviously, as 5T has suggested, there is a little bit of an amalgamation of the wiring approach between the '77 and '78 and mine appears to lean heavily toward the '77 layout. I know that inexperienced assumptions are dangerous but I am considering connecting a double to the existing single and adding the switch wire and harness wire there. That would give me the 4 connections the diagram shows - two from the meter lights, one from the tail light, (I hope) and one from the switch.
    I am not ignoring sound advice, I am simply proceeding cautiously 'cause a mistake here can be expensive and time consuming. I have clipped the short blue wire in the ignition switch and disconnected the blue black in the relay loom. I have one blue wire from the switch connected to the loom behind the double blue connector that contains the tacho and speedo meter light wires, (Pic 1& 2). I am about to join the second blue wire from the switch to the blue that sits in the ignition switch connector per 5T's suggestion and the '77 diagram. (Pic 3) but I will still have a single blue wire coming from the right side harness, (Pic 4). I assume this harness connection is essential.
    My apologies if you're sick of this but I have not yet begun to screw up.
    cheers
     

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  20. 5twins

    5twins XS650 Guru Top Contributor

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    OK, let's start with your new headlight on-off switch. It has 2 blues instead of a blue and a blue/black. That's OK, there's really no difference between the 2 wires. Look at the contacts in the switch drawing. In the "On" position, red/yellow (headlight power in) is connected to both the blue and the blue/black. In the case of your new switch, that would be the 2 blues. So, you don't really need to tell them apart. They're both connected to the same power feed (R/Y) so they are basically the same wire. Either could be considered the missing blue/black. Run either one to the ignition switch, the other to the single blue coming out of the double on the blue coming out of the main harness.

    So, you traced the tail light blue to the light checker but can't figure it out after that. We know that the tail light is controlled by the ignition switch on the '78SE so look there. You will find a blue/yellow coming out and running back to the light checker. This is the tail light power. In the light checker, it gets connected to the blue that runs to the tail light. This is why if you decide to eliminate the light checker, you must jumper the blue/yellow to the blue to get the tail light to work again. Removing the light checker breaks that connection.

    Being that you're dealing with a new aftermarket harness, the wires may not match up exactly to a stock harness. There is only one blue coming out of the stock main harness into the headlight bucket. You will probably need to trace the 2nd blue you have to find out where it goes. It may just be branched off the other blue back in the harness somewhere.

    Some wires change colors or connect to other colors as they run through the harness. The blue/black is an example of this. It ties into the instrument bulb blue on it's way from the RLU to the headlight on-off switch. This is an odd wire as it can flow current in either direction depending on the circumstances. With the key on, motor not running, and the headlight on-off switch on, it flows power to the RLU and the instrument bulbs (blue that branches off). Once you start the motor and the headlight safety relay kicks in, it sends the power into the blue/black wire to the RLU and the instrument bulbs. This turns your headlight on even if the on-off switch is in the off position.
     
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