Once I was on a long road trip, and while driving for hours the engine and electronics were just fine. But when we stopped for gas, it was all over. Speedometer would wiggle and nothing else. One guy tried to jump with no luck. Tow truck came to jump it and couldn’t until they ran up the engine and shorted the starter with a screwdriver.

Turned out it was a really bad internal short in the battery. It was consuming jumpstart power and couldn’t do anything. Swapping the battery solved everything.

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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)