I could not find on the forum what service selector switch does in MP 15DC switcher so I decided to post what I found. Below is quouted from WP SW1500 Operator's Manual. "Service Selector Switch This rotary snap switch is provided to select the type of locomotive service required. The switch has four positions; SWITCHING I, SWITCHING 2, SERIES (FORESTALLING), and ROAD (AUTO). The functions of the various positions are as follows: SWITCHING I Position - This is the normal position for yard switching. The load regulator is in maximum field position at locomotive start and the generator excitation circuit is set up to provide fast but controlled throttle response for switching operations. SWITCHING 2 Position - Locomotive operation in the SWITCHING 2 position is the same as in SWITCHING I position except that the engine idles faster in SWITCHING 2 position. The faster idle results in faster acceleration. This position may be used when fast acceleration such as for "kicking" cars is desired. SERIES (FORESTALLING) Position - This switch position is included with the SW 1500 switcher even though the motors are connected in permanent series-parallel with the main generator. The reason being that switchers with transition circuits may operate in multiple with the SW1500. In such case, the SERIES position is used in slow speed heavy drag service where series-parallel transition speed is reached so infrequently that changes in motor connection are not desirable. With the service selector switch in SERIES position, the load regulator is in minimum field position at locomotive start. Throttle response limiting resistance in the generator field excitation circuit is modulated by the load regulator. This provides smooth application of power for a softer start in road service. If SWl500 switchers are operating in consist or independently, the SERIES and the ROAD positions have the same effect. ROAD (AUTO.) Position - The ROAD position is used during moderate and highspeed road operation. At locomotive start the load regulator is in minimum field position and throttle response limiting resistance in the generator field excitation circuit is modulated by the load regulator to provide a softer start in road service. If the SW 1500 is operating in multiple with units that are equipped to make transition, it allows for a change from series to series-parallel on trailing units." Hope you find that somewhat usefull
I noticed that changing to "switching 2" position increases RPM in idle. I did not do enough services/scenarios to spot significant difference to be honest.
