I know what the SZL is but what is the CAPPL module?

 

it's basically the CCC.

 

So I am trying to continue with this retrofitting and am stuck on figuring out which SZL and Coil Spring that I need. Realoem.com only shows 1 part number for each and there is no differentiation between heated and non-heated. Part # for Coil Spring is 61 31 9 129 499 and the part # for SZL is 61 31 9 136 898. I found an auction that has everything I would need but it is from a 2006. This would not work at all on my 04 right? I know the steering wheel is different but are these two parts different too?

 

Tough to say on the SZL and coil spring... although for an '04 it only shows one part for each, I definitely had to change mine out when I added heat to my 2008 m-tech wheel. Try looking at a later year or two on realoem, as parts may have been updated as options introduced (it might give you a better idea of what parts can replace others). Another option is to check out bmwfans.info which also has parts listings but have more clear info as to which part can be used as a replacement of another.

Good luck! Having the heated wheel is awesome when the temps hit -30!