You need the "second vehicle system". This includes everything for the brakes on the towed. There are two models, one with a breakaway and one without. I wouldn't bother with the kit without the breakaway. Model 98160 is what you need. Then you will need a towbar and brackets to fit your towed.
2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft
Charter Good Sam Lifetime Member, FMCA, SKP
RV'ing since 1957, NRA Benefactor Life, towing '05 Odyssey