Lighting fault advice please

Discussion in 'Mech Tech' started by Bertiebot, Jan 22, 2022.

  1. Hi all

    I am trying to fix an odd issue with my headlights. It only affects the right hand side. The sidelights for fine but the dipped.full beam is the issue. Dipped works fine but when you switch on the full beam the dipped stops working. I have checked the wiring all the way from the headlight to fusebox and cleaned or changed connectors for fresh clean ones. The cables are undamaged over that run from headlight bowl to fusebox. I am assuming its an earth fault of some sort as why otherwise would one lighting circuit affect the other? I am a bit baffled as if it were an issue with the flasher switch on the steering column or the dashboard switch surely it would impact both sides, not just off side?

    Any thoughts of things to check would be really welcome!
     
    Bob Alatt likes this.
  2. If it's anything like a Beetle, and I admit it doesn't have to be, but this exact same set of symptoms was traced to an earth fault where the light fitting's earth is taken by a wire from the bulb's plug back into the body somewhere behind the light bowl itself.

    Try checking continuity from the earth of the lamp plug to the Bus body. If you don't get a beep, it's come loose at the body end of that plug.
     
    Bertiebot and Lasty like this.
  3. Dipped beam should go off when high beam is switched on, thats how it works.
    Dipped beam only stays on when you flash the high beam.
    If your lights are going out when you switch to high then its the high beam at fault.
    Have you tried swapping the bulbs ?
     
  4. Sorry, I didn't explain it properly. When I switch to full beam, neither work. The dipped goes off as well. I have tried other bulbs and its not that.
     
  5. Will do also try replacing the connectors etc. so its super clean
     
    nicktuft, Lasty and F_Pantos like this.
  6. mikedjames

    mikedjames Supporter

    The side light is earthing through the filament of the dipped beam and main beam bulbs on both sides . The sidelight and headlight is missing a working earth connection.

    Basically current goes through LA1 which is a 5 watt bulb, then because the earth is missing, it flows through the 55 watt filaments of LA2 and LA5 in series, and through LA3 and LA4 in series. All the time these are off they represent a good ground for a small light bulb.
    When you turn on dipped headlights, LA2 similarly will ground badly through LA3 and LA4 in series - result is LA2 will be a bit dim AND the main beam LA3 / LA4 will come on too.
    broken.png
     
    art b, F_Pantos and Bertiebot like this.
  7. Keen to know if you resolve this as I think I have same issue only with the n/s lamp. If you do resolve it, could you post a billy basic explanation of what was required? I’d appreciate it.
     
    Bertiebot likes this.
  8. nicktuft

    nicktuft Supporter


    As Mike says the earth connections all round need to be well and truly grounded to the chassis.
    Dodgy bulbs can sometimes be a problem as well. Just make sure they all work properly for peace of mind.
     
    Bertiebot and F_Pantos like this.
  9. Earth wires to sidelight and headlight replaced and all working as it should now - which is good! Needless to say I have found another job to do as my washer bottle is leaking around the electric pump (its an aftermarket one). They do keep you busy these buses don't they!
     
  10. mikedjames

    mikedjames Supporter

    If you install the electric pump with the motor down, it is doomed to leak into through the lip seal on the pump drive shaft onto the electric motor part which fills up and dies. There is usually a drain hole somewhere in the pump part near the pipework, best bet is motor pointing up or at least drain hole down.
     
    Bertiebot likes this.
  11. Its leaking between the motor and tank and was cheap thing already fitted. I am waiting for a £12 new one from heritage to arrive. As I had the kick panel off I topped it up and a few minutes later thought "why is there a wet patch on the drive? And the level was down to the motor seal line. Hey ho, at least its an easy fix!
     
  12. Might be a dying headlight relay. I had similar problems and turned out to be this.

    Sent from my AC2003 using Tapatalk
     

Share This Page