I have just purchased a secondhand witter towbar & electrics. I have
downloaded fitting instructions from Witter for the towbar but need
help with electrics which have a relay/unit of some sort which has SB2
from rydertowing on the case. plus the plug with the wires cut off. I
can map the wires to the plug pins but how do I connect it all to the
car?

Is there a halfwits guide somewhere  ?

Any help appreciated.

Chris