Loco runs out of control in reverse only!

[Vonsworld]

Hello

I'm new to DCC and am converting a DC layout to digital using a Select controller and all Hornby Loco decoders.

One of the Loco's I have converted to DCC is an old Hornby GWR tank engine. It works fine with DCC when running forwards, but when you select reverse it runs away at top speed out of control.

I've cleaned the track and my other Locos all work fine. If you physically turn the troublesome  Loco around and run it the opposite way around the track the same problem happens, it works fine running forwards, but out of control in reverse!

Has anyone encountered this problem before please or have any suggestions?

Thanks

Robin

[RDS]

I have not known this to happen in only one direction before but occasionally DCC Loco's have been known to run away because the decoder thinks it is on DC and sees full voltage applied to the track (which is how DCC works).

One of the CV's on the decoder is preset to allow running on DC as well but this CV can be changed so that it will not run on DC.  This normally solves the problem but I cannot recall anyone only have it happen in one direction but it would be worth a try. 

Having said all that, I am not sure that the Select Controller is capable of changing CV's so you may need to get a dealer to change it for you, or find someone with a Controller that can change CV's (like the Hornby Elite)

[Fishmanoz]

Given it is only in reverse, I believe your decoder is faulty, rather than it being just DC runaway. Easy to check, swap it into another loco and I think you will then find it running away in reverse. 

Take it back to the shop for replacement. Don't worry if you have cut off the plug to solder it into your loco, they should still replace it. 

And you can't turn off DC running with Select as it won't change the CV to do it. It is CV29 that needs changing.