After almost 10 years since taking delivery of the vehicle in May 1998, this is the first wire that failed. It appears that the original friction tape wrapping (black, cloth-based tape) of the wire harness was unraveling and some of the wires became exposed to rubbing on sheet metal surfaces behind the left side headlight under the windshield washer reservoir tank.
Ken

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2014 E250 Bluetec 4-Matic
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1996 Chevy Tahoe 4 x 4
2009 ML350 (sold)
2005 SLK350 (sold)
1999 E300 Turbodiesel (sold)
1998 ML320 (sold)
1991 300D 2.5 Turbodiesel (sold)