I went through the same with my my J. Mine was a runaway at one point as well.
Unplug pin 10 (the one furthest from the heat sink) on the Cruise M and put heat shrink on it. I pulled the 10 pin and removed the wire from the 10 pin and the associated plug on the mother board.
On the 4 pin from the motherboard to the Cruise M, unpin the pink wire and put heat shrink on it. I then used the wire I removed from the 10 pin and put in the 4 pin from the Cruise M to the 4 pin on the motherboard. Looking down on the Cruise M with the heat sink closest to you, the wire will go in the far right position on the motherboard too.
In the pictures I attached the pink wire is still hooked up. It will run this way, but I found issues with it. Do not run it with the pink wire in place. A side note, you will loose your flickering firebox. The center LED stays on like it normally does, but the others come on like ditch lights and will flash/oscillate when you sound the whistle. I have the Super Chuffer and Chuff Generator on the way for mine. The low speed operation with the cruise M is amazing.
Motherboard 4 pin:
Yellow, Black to IR, Blue, Black
Cruise M:
Yellow, Nothing (pink used to live here, went to IR), Blue, Black
