Rear Light Problem

[Mike.Morgan]

I am just getting my Huntmaster ready for its MOT, and am having a problem with the rear light.

The light works fine when the switch is in the L position, but then goes out when switched to the H position.

Its driving me nuts!

Any ideas??

[keith.mettam]

Hi Mike,
Not knowing if the wiring has been touched on the bike or not, the speedo bulb wire and rear light wire should go to the terminal connected to the centre of the Lucas lighting switch so that the rear light and speedo light are lit when the switch is rotated to either the 'L' or 'H' positions. From memory I believe it is linked to the switch centre via a tensioned / sprung metal blade. Perhaps this is too light / dirty when the switch is in the 'H' position and not making good contact ?

If you haven't a wiring diagram you can download DraganFly's Wiring Loom List from here :-

http://www.draganfly.co.uk/ariel_tech.html#20 (you may have to copy and paste this link in a new window if it doesn't directly work)

It seems to cover most BSA and Ariel models and Loom no. 1071 is for your model. It is just the main loom but may help you trace your fault.
If the light worked before and nothing has changed then take a close look at the lighting switch (as mentioned), the fault is likely to be there.

Good luck with it,
Keith Mettam.

[Mike.Morgan]

Cheers Keith,

I have just built the bike and have used a new loom from Drags. The rear light goes to position 5 on the switch which goes to the central pole.

I was thinking the switch (again new) may be faulty, not sure if I have missed something more obvious though??

[keith.mettam]

Mike you can prove the switch by selecting 'H' and then carefully shorting terminal 5 and terminal 2 (which should have the dip switch live feed connected to it) together. If the rear lamp lights (along with the headlight and speedo lamp) then the switch is the problem.
Regards,
Keith.

[Mike.Morgan]

Thanks for that, I will give it a try in the morning!

[Mike.Morgan]

Sadly it did not work, I think it may be something not right with the number 5 position as the speedo light occasionally stays on when the switch is in the off position.

[keith.mettam]

Sounds like a faulty switch, Mike. Hard to understand why though as they are very basic with terminals 4 & 5 connected in the 'Off' position, 3 & 4 plus the link to 5 connected in the 'L' position and 2 & 3 plus the link to 5 connected in the 'H' position. The battery (-6v standard) being supplied via terminal 3 in both 'L' and 'H' selections. It would be a good idea to double check your wiring and switch terminal connections. Back to basics.....Using the Drags drawing and assuming bog standard set up, you should have negative 6V at switch terminal 3 which is fed via a brown white wire from the negative terminal of the ammeter (note that the other brown white wire on this ammeter terminal comes from the 'A' terminal of the voltage regulator). This voltage is supplied from a brown blue wire directly from the negative terminal of the battery to the positive terminal of the ammeter. After checking the voltage at switch terminal 3 is there, disconnect the brown green wire (which feeds the rear light) from switch terminal 5 and connect it to terminal 3......does the rear light work ok now ? If so, then tail light wiring is good (which it should be as you said it worked in the 'L' position) so we are back to the switch again. If not then you need to check the loom wiring out further back to the tail light itself as you have now connected the wire directly to a good 6V battery supply (on terminal 3) so it should work.
Once again, good luck with it,
Keith.

[Mike.Morgan]

Got it sorted, after eliminating everything I was able to narrow it down to the switch itself.

And after some head scratching, I found a tiny gap between the copper strip bridging terminal 5 and the centre of the switch.

After removing it and bending to ensure it made contact with the centre, there was light!!!!

Many thanks again for your help Keith.

[keith.mettam]

Good luck with your MOT now, Mike.
Keith.