Hi all. i,ve trawled and asked on some facebook groups. but they keep pointing to there american multifunction switch. now i've replaced bulbs. on my 2nd brake light switch. fuses. but no brake lights. yet i have brake light on my trailer socket when i plug my mag lights in. is there something i'm mising on the back end.

 

Do you not have any brake lights on the vehicle or is it you don't have the high-mounted center one? If the latter, it is a long-shot but you might check the relay for it. On my USDM Blazer it is in the under-hood fuse/relay box.