M.T.H. HO 4-8-8-4 Big Boy Engineer's Manual page 28

The above list includes ALL F functions that an MTH PS3 engine could have. You
are free to change any of the above listed items to any F function position, 1-28.
For example, if you your engine came from the factory without a smoke unit but
you added one at a later date you could swap out any of the F functions, 1-28, for
the Smoke On/Off and the Smoke Volume.
So, using the example above of moving F4 to F28 here are the steps:
1. Refer the MTH Supported CV table to see what CV the destination Function is
assigned to. In doing so, you are looking only for the Low Byte CV location. In
this case it's CV170
2. Using your DCC system, bring up CV programming for CV170
3. Now tell the engine which F-Function you want to write at CV170. So, looking
at the Function ID table above you can see that PFA is a value of 23
4. Using your DCC system, enter a value of 23 for CV170 and hit Enter. You have
just re-assigned the PFA sound to F28 on your DCC controller. The engine will
give you a two horn blast indication. Note – You've also left an empty location
where PFA used to be (F4)
5. Now you can fill that location with whichever CV you'd like. For this example
we are just going to move the Feature Reset up to F4 (we're just swapping F4
and F28)
6. Since F4's Low Byte is CV122 then bring up CV programming for CV122
7. Now tell the engine which F-Function you want to write at CV122. So, looking
at the Function ID table above you can see that Feature Reset is a value of 29
8. Using your DCC system, enter a value of 29 for CV122 and hit Enter. Your
engine will give you a two horn blast indication
M.T.H. HO 4-8-8-4 Big Boy Steam Engine
28