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Headlight failure - wiring or weak battery?

Discussion in 'Maintenance and Servicing' started by Brett, May 12, 2016.

  1. Went to start the bike tonight (CB400) and noticed the headlight didn't come on with the ignition turned on. Wasn't the globe or the fuse. Stuffed around a bit and started engine a few times and eventually they came on so I headed off. Later when I was about to come home same thing happened. This time I just started the bike and about 30 seconds later the lights came on. Stopped for petrol and this time it started up with the light working straight away. Next stop was for about 20 minutes and same problem with them starting up after a minute.
    Is it possible that there is something wrong with the battery?
    Though maybe it isnt holding its charge and the lights kicking in when it is running and charging - but would it still be able to start the bike if this is the case?
    All other lights work.
    Any suggestions of possible simple problems are welcome as I cant really afford to take it somewhere to get it checked out unless it is really necessary.

  2. Headlight relay
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  3. If it was a battery the bike wouldn't have started!
    Swap out the relay as suggested, sometimes they get stuck or corrosion starts forming on the connector making them act a little trippy.
    As its not flickering on and off while riding that suggests its not a loose cable
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  4. Any tips on where to locate this? i haven't stuffed around with electrics at all on the bike yet.

    I have also had another suggestion from a mechanic I called (I called 2 mechanics and an auto-electrician and Brett @ Mad Biker was the only one who came up with this great idea) - that it was a dry or dirty contact in the r/h starting switch box. He said that if it happens again to test by flicking the button lightly enough to not activate it and I may see the headlight switch on - of which I tried and it did do as he said the one time I got it to fault when i wanted it to.
    So I opened it up and checked it and sprayed some contact cleaner around. Will see how I go for the next few days.
  5. Yes this would have been my guess, the starter switch disconnects the headlight when pushed so that the starter motor gets as much of the battery capacity as possible. They have a habit of getting gummed up. You can also disconnect the battery and activate the starter button a number of times. The contacts are designed to be self wiping so along with your contact cleaner this can fix the issue.
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