2001 Silverado trailer wiring question, need help

I have a 2001 Silverado that I am wiring in a plug for my 5th wheel... there is one Light Blue wire that is coded/marked CHMSL Does anyone have any idea what this wire is for.. the other wires are marked

Brown - parking lamps
lt green - back up
drk green - R turn
yellow - L turn
Drk Blue - Elec Brakes
Red - Battery
White - Ground

Lt Blue - Chmsl ????????? this is the mystery wire???

please drop an email to [email protected] asap

We think we have found the answer???? found the below statement on a google search


beams were added for safety along with a center high-mounted stoplamp (CHMSL).