So I am kind of anal about knowing what options are available for my truck. There are two square connectors under the ash tray. one is for the electric brake controller and I thought the other was for the ACPM (AIC); well agter buying the ACPM and discovering that it is impossible (without undo force)to plug a round connector into a square connector. After finding the correct plug for the ACPM I'm left with the delemia that I have a plug that I don't know the function of. Note this is not the data port (it's to the right of this plug) This plug is back to back with the trailer connector. Anyone out ther know what this plug is for? /ubbthreads/images/graemlins/shrug.gif Please help! Thanks.