Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

Hi/Lo Beam problem

Discussion in 'Technical and Troubleshooting Torque' started by mattb, Feb 6, 2008.

  1. I've been having a problem with my high beam, and now with my low beam. Originally, the low was fine, but the high developed a fault - it would come on and off, in a waxing and waning kind of a way. Quickly that turned into not remaining on at all. When I turn it on while riding, there is nothing, then suddenly it will come on, wax and wane for a few seconds, then go off and not return. That's still the case, and I've been surviving on low beam only, but now on when set on low it flickers between high and low. I replaced the switch block so that's probably not the problem. The headlight is a sealed beam unit and hooking it directly to the battery it'll give a distinct high OR low beam. The thing is the high beam comes on when I rev the bike above around 3000RPM. I've already had a go, but I guess I've got more wire inspecting to do, but my main question is: The high beam flickers on (over-riding low beam in which position it is set) when I rev over 3000RPM, and flickers more violently the higher I rev. I'm assuming this is simply because of the vibes of the 500cc single, with the assumption that there is a loose / exposed wire or connection somewhere. But could it be something else in the system other than the wire and vibes, but having to do with the rise and fall in revs? This problem is creating anxiety in my night-riding - I am flashing drivers as far as they're concerned (I think that explains the bit of aggression I copped tonight).

  2. Sounds like a dodgy connection, either a frayed wire, bad earth etc.
    Have u tried wriggling the wiring harness with the lights on?
    ( stationary of course ) :p
  3. two thoughts:

    - sometimes bulbs don't fail completely. Sometimes they fail then arc across again. Other times the glass comes a bit loose from the seat. So replace your bulb even though it is unlikely.

    - Secondly, voltage regulators look a bit like this when they go.
  4. Good suggestion.

    Otherwise you have a wiring fault - the vibration of running is making and breaking the circuit. Check between the switchblock and the lamp. Also check (more likely) the contact for the high beam part of the lamp (in its socket), it could be worn or the metal weak (it is a spring-type contact).

    If it was a regulator that would affect both beams.


    Trevor G
  5. Thanks for the replies.

    Having done a decent wire inspection (though not absolutely comprehensive) before posting, I suspected the two problems you mentioned ibast. It's a sealed beam unit, so I might have to just replace the whole thing as part of a test (or cut the wiring and run through the Boulevard at night with a lamp from a friend's wrecked bike).

    The switchblock is new and I wired it myself (trying to rectify this problem), and the head-light socket is simple : three prongs from the headlight going into a watchamacallit - a tight good fit. I've cleaned it and the other connections. Could the regulator going bad cause the flickering between high and low beam that I mentioned when set to low beam but increasing the revs, or would it simply go on and off like it does when set to high-beam?

  6. Could also be a relay or a wiring fault close to the headlamp, like the connectors or similar.

    Regards, Andrew.
  7. Unless your battery is absolutely dead a failing regulator will just allow the battery to over or under charge. A good battery will stabilise the voltage applied to the lamp(s) and prevent strong fluctuations. Normally.

    Anything can happen. If you run a lead from the battery (or any other 12v supply) to the lamp socket and it doesn't fluctuate then you know that it is wiring related. If it still plays up (and you have not connected directly to the lamp itself) then you probably have a faulty lamp. Had 2 faulty car ones last year. Intermittent.


    Trevor G
  8. Trevor is right, it is unlikely to be the regulator. I don't think it would cause the switching thing.

    Check out your earth circuit from the back of the bulb.