Rear tail light issues

[EddieT]

Hi guys apologies if this has been covered previously as I’m new to the group. 

I’m having issues with the rear tail light, when the engine is running the rear light does not come on. The brake function works fine and does illuminate when brakes are pressed. However in operation if I was to drive at night I wouldn’t have a rear light that would show to vehicles approaching behind me.

Any help on what the cause could be would be appreciated. I have checked the bulb and it is in good order.

[Art]

Assuming the bulb lights up when the engine isn't running, engine vibration is causing a break in the circuit somewhere between the fuse (assuming you have 12v at the fuse) and the bulb filament (assuming you don't have 12v at the bulb).

1) check the bulb filament or replace the bulb with a known good bulb, note its a dual filament bulb.
2) check the fuse for continuity or replace the fuse with a known good fuse.
3) check for loose connections, has the loom been extended via a relay triggered from the rear light?
4) check the circuit, multimeter in hand check for 12v from the bulb holder and work back through each connection to the fuse.
5) check for ground to chassis.

Note all checks will need to be carried out with the engine running. If I was a gambling man I'd wager a failed bulb filament.

[EddieT]

Hi thanks for the response. I’ll give it ago and start with replacing the bulb and if needed stripping the back end down back to the fuse. Just one question tho. Where is the fuse for the tail lights likely to be. Behind the battery?

Thanks again.

[Art]

Its just the main fuse that is behind the battery (if you have ABS those fuses are alongside the battery). The fuse you want is in the fuse box which is located under the pillion seat just behind the riders seat. Lift up the rubber shroud and the fuses are all conveniently labelled on the lid of the fuse box which hinges open at the side.