Woo Hoo. I installled an MRC 1645 in a P42. I didn't know why anyone would want diesel sound(duh!, now I know). That said, I don't ALWAYS want diesel sound. Doubleclicking the headlight did not do it. I can shut the sound off, if the loco is idle, by pressing F8 3 times. but it won't move until I hit F9 and start the sounds, or reverse the direction (which also starts the sounds) Hoping it isn't F23, unless there is a way to fast forward therough the 15ish volumes Also CV 49 (sound on, off) seems to need to be set on the program track. I tried it on the main and got no change. This isn't very useful either.