No there are 2 systems,
the 2K4(78-79) and 2X2(79only) Dt 175mx had the following:
Brown, red, white/red,black They come direct from the mag.
orange, black/white, black, come out of the loom.
The 4J4 (80-85) Dt175mx and the Dt125mx (4J3) of the same period had the following:
Brown, white/red, black. They are direct from the mag.
Orange, black/white, black, coming from the loom.
All of these bikes have the orange feeding the coil, the black and white kills the engine via the handlebar stop switch and the black is the battery return/negative.
On both bikes there is also green/white, light blue and yellow.
The yellow being the lighting feed to the ig switch, the light blue the neutral light earth and the green and white which turns to white in the loom?? charges the battery via the rectifier.