I recently fitted an after marked head unit and whilst digging through my old cables in garage I found my kenwood to vauxhall patch lead( to make steering wheel controls work) it was installed on my old vectra b, will it work on my 2003 pre f/l signum??? If so how do I wire it in, I can't remember I plugged all the plugs into relevant slots but there is a brown wire on the patch lead, being brown I assumed it was earth? But when connected it didn't work so either the patch lead doesn't work or the brown wire goes elsewhere

Thanks in advance