WHITE WIRE BLACK TRACE?

Hi All
 when I got the LTD,    the wiring harness was hanging out of the bike. I have been trying to put it back where it belongs with pics from the internet. I am down to a few wires at the battery box. I have a white wire with a black trace and a female bullet connector left... My diagram says its a horn wire.   Any guesses to what it is for? 
  TIA
  Steve
  

accessory lead w 10A fuse. wire should go to a nearby acc fuse box assy.  mounted to a small bracket. should be visible under the LH side cover. the other acc wire. blue/white. goes to the headlight bucket. 

kz.bike-night.com/media/KZ750-H2-US.jpg

H1Vindicator  
 Thank you!