Put a new decoder in my 4th loco today. (Lima motor). I've done one with this sorta motor before with no problems. Always check and recheck correct connections before powering it up. Plastic chassis and motor is isolated. Put it on the track, and without even selecting it, the headlight comes on, for about 3 seconds, and the decoder lets out this quite audible squeal, then the DCC power unit shows a short on the layout. Checked the decoder with a multimeter, and it shows a complete circuit between the red & black wires (track pickup) and grey and orange wires (+ and - motor connections). My other decoders don't show these connections as a completed circuit. I would sugest to myself the decoder is cactus. I put another decoder on the loco and it's fine. Could I have blown the decoder up somehow? if so, what sorta thing would do this to a decoder? Would you consider the decoder faulty, and need to be returned under warranty?