I am trying to figure out the 7 solder connections on the printed circuit board on the dcc decoder. They are labeled M+, M-, R, L, L+, 1- and 2-. Some of these are obvious such as the M+ and M- for the motor. I am thinking that the R and L are the electrical pickups from the trucks. Not sure on the L+ and the 1- and 2- but two have to be for the front and rear lights.

I have a N scale Peter Witt Street Car with DCC and would like to add sound to this unit. Will I need to change the decoder? If so what decoder should I use?