This happens because someone cheaps out on the metal used on the contacts. If the harness was repaired under the recall and the pump wasn't, then it's possible only half the problem was fixed heading towards the same problem happening again. Even worse, if the connectors on the replacement harness aren't much better than the original ones.

__________________
1988 325is (purchased new) sold
2004 X5 3.0 2005 X3 2.5
2008 X5 3.0 (new to me)