[A/S] Trailer wiring question

[SHMossLanding@xxxxxxx]

Just got a 2000 GMC pick-up.  It was all set up for a 5th wheel, although it 
has a regular hitch and was wired for electric brakes and has the 7 point 
connector.  My question is,  everything is correct on the connector, with the 
exception of the back-up lights, they are on all the time.    Can anyone tell 
me the best way  to see which terminal does what on my unit.  It has a tag on 
the harness, and said the light green wire would go to the backup lights, 
which on this plug is the center pole. It shows facing the male portion  1 
o'clock (+)  3 o'clock right turn/tail  5 o'clock electric brake,
7 o'clock (-)  9 o'clock left turn/tail and 11 o'clock running.  center pole 
back up.  I cut this wire but still stays on all the time,  plus lights the 
back-up lights on the pick-up all the time.   Well, any advice appreciated.  

                                                 Chuck & Lynn
                                                 1965 Overlander