Runaway Train!

[Hugha]

Yesterday I was moving stock from my main layout to the fiddle yard using two locomotives, the first ran perfectly but the second stalled it then restarted and ran at full speed (about 1/2 of the speed set on the controller) and would not respond to the controller, it was only by switching off at the mains would it stop. Any ideas what could have caused this? I use a powercab controller and the layout is in the garage and whist it was warm in there both the main and side doors were open.

[Walkingthedog]

Dirty track or dirty wheels/pickups. The decoder is getting a bad signal, thinks it is on DC track and whizzes off. If you disable DC running on the decoder it won’t do it.

[Hugha]

Ok thanks, suspect it might be the wheels as I had cleaned the track in that area last week.

[Brian]

Hi
Uncontrolled runaways are caused by the issues as described by WTD.
If you do not need your loco(s) to run on DC powered rails, then its highly recommended to turn off DC operation in each locos decoder via CV29. Setting its value to normally 2 or 34. That is 4 less than the value read in CV29 originally e.g. read CV 29 value and it shows 6 then make it 2.