Brake Warning Light

check your alternator brushed and clean the copper rings with a hard eraser and clean with electronic spray to remove eraser bits and any crud

low voltage is indicative of brushes and alternator


also if lead acid battery check level and replace missing acid with distilled water

clean battery connectors then if still a problem clean grounds at motor and frame

this link also has in depth charging system info
The Ultimate Relay, Switch, Sensor, and Diodes Guide

 

thanks,will check all that and report back

 

update,checked all above.battery level was low on 2 of the cells and filled with distilled water,only checked battery a couple of months ago.on startup battery light went out and charging was 14.6v.think the battery may be on the way out will keep a check on it.

 

update,have been out on the bike three times since ,battery seems fine but the battery warning light stays on all the time (resistor fitted see above)

 

You need to revisit this. You must have continuity through the ignition switch W/R wires or you will get the battery warning.

 

went through and cleaned connectors again and now light goes off and stays off,although not been out for a run yet.