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1981 Honda XL 500 S wiring problem

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I've got a wiring issue I'm trying to get a handle on and not making any headway. My turn signals and neutral lamp seen to be crossed up somehow and when I signal left the signals flash but the indicator on the handle bars alternates with the neutral light flashing also. I get nothing when I try and signal the right side. I've traced wires, looked at the wiring diagram and can see no way there is any connection between signals and neutral light. The tank is off and all wiring underneath looks fine, nothing bare or cut, and nothing chafeing. Has anyone experienced a similar problem; and if so, how did you trouble shoot it? Thanks for any advice.

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Can you tell us whether this problem just suddenly started occuring or have you been doing some wiring work on the bike,,ie Have you been working on rewiring the bike or have you been doing any wiring work behind the headlight,,??,That's where you should be looking for the problem as that's where the problem probably lays,,All connections that'd cause your issue are behind the headlight.,short or wrong plug in something behind there.,

Normal Honda wire colours for front and rear indicators are Orange,,(left indis) and Light Blue (right indis),,Normal for indicator dash lights is I think is an extension of both orange and lightblue ,,Trace whatever colour comes from the neutral dash bulb (possibly lightgreen/red) and make sure it's not crossed up somehow..,Check all the Earths are good as well,,(Dark Green) No joy anywhere there then check the Light/Horn/Indi switch assembly,,Watch out for flying bits should you strip it down to basics,,Lots of little ball bearings and springs in the switch assembly,,much care needed if disassembling or you'll lose parts for sure..,Always break it down over a nice clean large rag/sheet or deep inside a bucket to make finding flying parts easier..,

I'd leave that switch assembly alone until you exhaust all other possibilities,,the neutral weirdness is unlikely to be caused by it,,the lack of one lot of indis working may be but only through a wire broken inside the switch,,.

Make sure you haven't got the flasher units wires mixed up with the neutral,,pretty similar in colour,,LightGreen/red==>neutral,,,Flasher unit==> lightgreen and a black

Edited by Horri

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Hi Horri, thanks for the tips, I'm still looking over things. Wires to flasher are correct.

Yeah, I've had the whole bike apart for restoration and signals and light all worked before disassembly. New battery, dielectric on connectors, etc. Initially, after reconnecting everything the signals worked on both sides up front, rears were not connected at that point but had no neutral light. Took side cover off covering sprocket and neutral switch to check connection and found it to be good. Turned key switch back on and now had neutral light but that was when right signal called it quits and the left side worked but indicator flashes alternately with the neutral light. Shifter turns light on and off just fine has no effect on the turn signal either. Your wire colors are just like what I've got and match the wiring diagram as well. I haven't gone back inside the headlight bucket yet, but will. It was fine even after completeing headlight assembly and putting all wiring stuff back inside it. I have a bare metal ground connection between harness ground connector and bike's frame, like wise on coil and the metal rack holding the ignitor and rectifier.

I'll keep looking and post something when I have answers.

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Wiring can be a dog at times. Just rewired my 89 XR600 twice trying to find problems,,It's wired up exactly the same as an XL500,,even added a battery,,.NZ 600s are totally different in the wiring from US XR600s,,we run all the road gear on them ,,horn/indis/headlight/Tail/brakelight..,Completely stripped the loom as I couldn't get the headlight working, Turned out the Reg/rec and the voltage regulator were both poked., If only I'd known that before spending weeks trying to figure out why the Headlight/Tailight wouldn't work correctly., I did have a similar thing as you going on with mine at some stage during the rewire but am unsure what I actually did to fix it,,Double check all the wires to the Tailight and any other Green or Blacks in the harness,,Pretty sure I had one of the Blacks hooked up to a Green and that may have caused the weird flashing behaviour I encountered.,Kill switch wires,,double check them for the correct plug in connections,.,Can't remember now but as I say double check everything,. No shortcuts with wiring unfortunately ,,well not for me anyway,,if I can't see what I'm dealing with I get kinda lost in the ohms/watts.,

I'll post up another XL500 diagram for you just in case your ones a bit different or wrong in the manual,,The one belows straight from the 500s shop manual.,Save it from where I post the diagram to your computer and open it with your browser (Firefox,,InternetExplorer) for the blow up view.,Left click the mouse on the diagram in FF or IE to get blow up.,

http://imageshack.us/photo/my-images/838/xl500400.jpg/

Edited by Horri

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Thanks for the wiring schematic, Horri. It is much more detailed in specifying what is a plug in or multiple connector block, etc. Wiring issues will definitely try your patience which is why getting all bent out of shape is generally counterproductive, but unfortunately tends to be one of my less desirable traits. Once I calm down and return to rational thought things go fairly well. :0 I hope to make more headway later today but have to make a trip to the airport to pick up a family member coming in for New Year's holiday. I will pick up a new 1154 stoplight and park bulb and flasher on the way though. The nubs on the old bulb were worn down due to age and vibration and weren't making contact unless you wrestled the bulb around in the socket. So that just leaves getting the signal thing sorted.

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So I pulled the headlight out of the housing and rechecked all connections and color coding/plugs etc. there and found nothing loose or mismatched. Unplugged and replugged all connectors. Still had same issue. Removed bulbs from signal light sockets and checked bulb tips for wear where it meets socket connection and added dielectric grease. Right hand signals begin working as did the tailight after replacing the bulb which still worked but only if you jimmyed it around. Contacts on bulb worn down due to vibration presumably and working well now that I replaced it.

That said, now all the signals work properly but the tail light flashes also when you signal in either direction. Plus, when you switch on the ignition the tail light park filament lights up. I don't know if that's normal or not. The engine has to be running for the headlight to operate but I don't know what the park light in back does usually. Any thoughts?

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As a general rule of thumb on electrical issues that defy explanation such as weird flashing and such. Check your grounds. If ground path gets disrupted it will find another way and often that is another signal bulb or other component.

Make sure of polarity at the bulbs and right bulbs, not a single filament in a double hole or something like that

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As a general rule of thumb on electrical issues that defy explanation such as weird flashing and such. Check your grounds. If ground path gets disrupted it will find another way and often that is another signal bulb or other component.

Absolutely true and I spent most of my working career as an electronics tech. Is your bike made in one of those years that the battery was only for the tail and brake light and thats why the headlight is only on with the motor running......?

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Thanks Dave, I'll look at the grounds again tomorrow. I'm not sure how I can get any more grounded than it already is but something sure isn't correct.

Motox, the headlight runs off the alternator and the signals, horn, tail light, neutral, signal, high beam indicators, speedo lamp, are off of the 6 volt battery.

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>>don't know what the park light in back does usually. Any thoughts?>>

Do you want to know its usual behaviour,,if so,,It should come on when you turn the key on and the headlight switch on even with the bike not running,,brake light should also work without the bike running as should the indicators and horn..Headlight should remain dead until the switch is moved up another notch and won't work without the engine running although if you have a small running light in the Headlight as well as the main Hi/Lo bulb it should light without the engine running with the Headlight switch in the run position..,That is the way it works on my 600 which is wired up the same as the diagram I supplied.,,I dunno if maybe the Reg/Rec could possibly be defective and maybe causing the issue,,I know both the reg/rec and regulator were stuffed on mine and it exhibited that weird flashing behaviour I described during my problems,,Trouble is I can't say for sure whether that was the cause as the job dragged on and on and I lost track of the final cure..I do know I had a wrong wire plugged in around where the kill switch.ignition wires plug into the loom,,think it was a Black I had running to a green by mistake,,Check the Blacks is the only other thing I can add as well as double triple check the brake light connections and the tailight connections for the correct orientation ie,,(plugs,,colours). None of my indicators,,headlight,,tailight are mounted metal to metal, (or metal to frame if you like) nor is the horn ,,the ground wires (Greens)do the grounding duties for my entire system., Got to watch some of those Blacks that actually run up to the indicators as they are really green,,(ground),,easy confusion there.,

Edited by Horri

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Horri, thanks for the heads up on the tail light park filament operation; at least I know it's normal for it to light when key switch is turned on.

I did check my signal wires running into the various connection points and made sure that black wires with light blue or orange plastic bands went into the proper connections as well as the black leads with the green band being connected to the green ground connector.

What I think I will try next is to make up a short piece of wire and add an extra ground wire between main harness and frame/coil and see if that helps. You are right about all of the various items grounding back to the main harness and then the harness green wire on to the frame at only one connection point that I can see, and I checked that for good bare metal contact, free of paint which might interfere with making a good ground.

I'll see what happens and post the results.

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I had a ground wire break in the harness on my 600, which disabled the headlight one night ride. I had to follow a buddy and ride from memory of what I could see in his headlight. Ran an additional ground and that is how it is today.

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Hi all,

I am having a similiar issue with an 81 XL 500. Since this thread is fresh in everyone's mind, I thought I would get your thoughts.

1)Purchased new battery and with bike running, left turn signals turned on and flashed. Right turned on, but did not flash. Any suggestions? Is it possible for them to turn on and have a good relay but have a disconnected wire?

2)Several hours later, while not touching wiring any more(purposley) the bike was back together and no signal lights, and no horn. This is with just battery and while running. Am I correct that there is only one fuse off the battery? Any other obvious things I could have done(bumped knocked off, etc.?)

Thanks,

Mark

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there is only one fuse, if it is blown you will have no taillight or blinkers or horn with the engine off. Oh, neutral light and gauge lights too. Headlight and ignition is AC.

Turn signal not flashing on one side if both lights light, my guess would be bad ground on a bulb. Usually if that is the case, it will be dimmer than the other. Possible wrong bulb too since the turn relay is load dependant. I used a Napa el11 (I think that is the number, but also from memory,) relay on my bike with it's combo of LED and conventional signals and it figures it out and blinks at the right speed.

There is a junction plug where all wires meet behind the headlight too that can get corrosion (resistance) from weather exposure over the years.

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Thanks Dave. I found the main issue was that the new battery I bought was not fully charged. I guess it takes a long ride for the bike to charge it. I took it back to shop and had them charge it. I now have blinkers on both sides. Strong battery is key on this 6V system. I also found that the aftermarket replacement light (should have bought OEM) came with a 12V bulb. The lights flashed more quickly after swapping with 6V. It seems the electrical is very temperamental. And, of course, the bike is 30 years old. The last owner neglected entire bike. My next step will be to clean all the connectors. I think I will be good to go after that and they will run even more brightly. Thanks again for your input.

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Looking for more advice: After having a battery connected that was likely 90 percent charged (I did not have time for store to charge completely), the battery eventually went weak enough not to power signals and horn.

I now have the battey completly charged. Using a Fluke digital electrical meter, it reads 6 volts. When I put on bike while running the meter will not jump any higher( The Fluke would have to go to 7, there are no tenths). However, when I remove the battery and put the meter on the positive and negative coming from engine (Rectifier/Regulater, I assume) I get 1-3 volts.

Does anyone know what this voltage should be? Should it actually be 6V or should 1-3 volts(depending on rev) keep this battery charged?

Will anything be damaged not running a battery at all, dead or charged)?

Thanks

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With no battery I was getting 4 volts on mine. With the battery to power the field coil it puts out 7.3 volts. Troy341

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1. I do not think your headlite will work unless bike is running (AC power)

2. You should have 7 plus volts DC coming from regulator/rectifier to battery

with bike running.

3. All your electrics except headlite should have 6 volts from battery with bike off

and ignition switch on.

4. Sounds like you may have a back feed to nuetral lite or a bad ground somewhere

5. I think all lites/switches have thier own ground wire, so lots of grounds.

6. You can hook up a test lite (big one)to one side of flasher with that side wire off and see if it works.

if not I think old VW (6 volt) will work.

Edited by seehogs

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After going through and simply cleaning all the connections, I am getting 7V at idle. 31 years of grime, maybe. Battery holding charge will be tested while riding next few days.

Is it normal for the XL's tail light to dim (alternate) with the blinkers? It almost seems like a safety feature, but I am thinking it is just the load from the blinker switch. My concern is the speedometer light dims too. If it is in neutral, the neutral light will also dim.

Thanks,

Mark

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"""Is it normal for the XL's tail light to dim (alternate) with the blinkers? It almost seems like a safety feature, but I am thinking it is just the load from the blinker switch. My concern is the speedometer light dims too. If it is in neutral, the neutral light will also dim.""

I'd have thought the indicators horn etc are run from the battery. Dimming of lights when one things turned on is normally the behaviour of a non batteried bike,,ie every thing's running from the Stator and it's a bit gutless to handle multiple things going at the same time..Maybe try some lower wattage bulbs to see if it cures the dimming.

Edited by Horri

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