How can I disable 4G LTE on stock samsung (SGS3) or CyanogenMod? My carrier, Sprint, has a lot of weak 4G coverage.  In areas where I only have one 4G bar, the internet doesn't work.  Every connection times out.  However, these areas often have moderate-to-strong 3G coverage.  In these situations, I would prefer to connect to the 3G network instead of the 4G one.  Is there a way to disable just the 4G connection?  I am looking for a solution in ether the stock Samsung OS shipped with the SGS3 or in CyanogenMod.
You can use the code *#*#4636*#*# in caller app, you will find a menu called 'Testing', enter in phone information and then in 'set preferred network type' select 'WCDMA only' or 'GSM only'