# Changing CV3 and CV4 on MTH with Digitrax



## D&J Railroad (Oct 4, 2013)

I have read the manual that comes with the Proto Sound system in my SD70Ace and it says to do any programming on the main. It lists CVs 3 & 4 as CVs that can be changed with a DCC system. I've tried changing them but it's not taking.
Any suggestions? I have tried setting the loco off the track for about 15 minutes after doing the programming on the main, but it's still not adding any momentum to the acceleration or deceleration.


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