Yes, I know that was a wild guess. But I also found this:

Word Origin & History. serape. type of shawl, 1834, from Mex.Sp. sarape, probably from Nahuatl, but exact source difficult to identify source because there ...
dictionary.reference.com/browse/serape

I think these words can hardly be related, while écharpe, sjerp, Schärpe were in use In Europe before the 17th century. A Spanish Etymology site does not regocnize the word se-sarape.So I am just curious (bad habit)about the link between écharpe/sjerp/Schärpe and serape when there is no obvious Spanish intermediar.