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Headlights & Sidelights Problem

Discussion in 'Mechanical' started by Wazza, Jan 2, 2014.

  1. Wazza

    Wazza ZX14R +

    Messages:
    79
    Hi guys,
    My 1998 Suzuki GSX750F has just failed its MOT on sidelights not illuminating. I changed the bulbs (which were blown) and tested them, at first they didn't come on but after a few tries they did illuminate. The problem is that when I switch the headlight/taillight on the sidelights turn off! I've never been great with electronics so have turned to you guys for some enlightenment before I start ripping it apart.
    Only thing I've noticed is that the front sidelight connector is corroded, which I originally blamed for the bulb blowing, possibly for the rear blowing as well (only the one filament blew in the double filament bulb).
    Thank you in advance!
     
    Last edited: Jan 2, 2014
  2. BlackHornet

    BlackHornet Look before you turn Staff Member Moderator +

    Messages:
    7,985
    do they need to work when the main light is on for the mot ?

    I thought most sidelights are meant to turn off when the main lights are on ( older bikes anyway as news ones are always on )
     
  3. Wazza

    Wazza ZX14R +

    Messages:
    79
    It's the entire circuit that lights the dash/dials, front and rear sidelights that switches off, thus when I switch the headlights on the dash switches off and also the taillight (being a sidelight as well as a taillight) switches off leaving no illumination from the rear of the bike.
     
  4. lost

    lost Samsung leaflet fetishist +

    Messages:
    865
    try some electrical contact cleaner on the handle bar switch and flick on and off a few times also check earths remove and clean then replace after that check connections and relays
     
  5. Roadwart

    Roadwart Administrator Staff Member Administrator +

    Messages:
    6,720
    Is this the bike you had an off on a while ago? If so, have you checked for a short somewhere?
     
  6. lost

    lost Samsung leaflet fetishist +

    Messages:
    865
    excuse me im short and have not fell off for 6 months ;)
     
  7. Roadwart

    Roadwart Administrator Staff Member Administrator +

    Messages:
    6,720
    You have to ride to be able to fall off mate ;)
     
    lost likes this.
  8. Wazza

    Wazza ZX14R +

    Messages:
    79
    No RW, this is a bike I bought two weeks ago, hasn't been looked after very well. I was hoping to not have to get too involved with the wiring, but will bring my multimetre home from work tomorrow and check some circuits. Thanks :)
     
  9. Roadwart

    Roadwart Administrator Staff Member Administrator +

    Messages:
    6,720
    If it hasn`t been looked after I would start at looking at the connections for corrosion, as you have previously mentioned you`ve spotted some.
     
  10. BlackHornet

    BlackHornet Look before you turn Staff Member Moderator +

    Messages:
    7,985
    a guy at work has the same bike I will see if he has come across the same problem before.
     
  11. Carnage

    Carnage Race Rep +

    Messages:
    775
    as said clean all corroded lamp holders and id go a far as opening the switchgear and running a piece of emery cloth over the contacts and checking the operation with a multimeter. if the switchgear is going open circuit when you switch the headlight on unless your a dab hand at that sort of repair find a second hand replacement.
     
  12. Wazza

    Wazza ZX14R +

    Messages:
    79
    Thanks for your advice all, I won't have a chance to look until until Sunday as it's dark by the time I get home from work.
    Can anyone explain how the loom is wired for the head/side lights and switchgear? I assume it's all a low voltage circuit so would it have a relay, or just a simple series/parallel circuit? If it's wired how I'm imagining it's wired (with the side light circuit splitting in the switchgear and joining onto the headlight/main lights circuit so they stay on when main lights are activated) could there be a break at the main light switch contact which would cause the side lights to go open circuit?
    I'm just speculating here as I've never opened up a switchgear with intention..
    I'd guess that because the front side light connectors are corroded that caused the bulb to blow, subsequently causing the rear bulb to blow and possibly burning out the connector at the switchgear.. sounds a bit far fetched but I know these old bikes don't cope well with random resistances through their circuits.
     
  13. BlackHornet

    BlackHornet Look before you turn Staff Member Moderator +

    Messages:
    7,985
    I spoke to simon at work and while he has not had this problem he did have an issue where all his lights turned off when turning from high to low beam when riding.
    He said it was an easy fix once he found the issue which was behind the main light, there is a small panel just above the headlight with just 2 bolts to undo. his was a wire that was totally cooked so he just soldered a new piece in. He did say he had to just keep testing the circuits until he found the faulty one and then just checked the wire.
     
    Roadwart and Wazza like this.
  14. lost

    lost Samsung leaflet fetishist +

    Messages:
    865
    id check handle bar switch 1st
     
  15. Wazza

    Wazza ZX14R +

    Messages:
    79
    Good news all, I completely dismantled the front sidelight housing and removed the contacts, cleaned them up and reassembled, then stripped the handlebar switchgear and checked connections and cleaned them with electrical contact spray. Hey presto all works fine now! Thank you all for your advice and input, much appreciated. MOT on Thursday, just gotta increase front brake lever reserve travel now.
     

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