I would start with a fresh battery. My Volvo 780 wouldn't start, all the lights would come on but no start, everything looked normal. Put in a new battery when I found out it was still under warranty and it started right up.

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1979 Black on Black, 300CD (sold), 1990 Black 300SE, Silver 1989 Volvo 780, 1988 300CE (vanished by the hands of a girlfriend), 1992 300CE (Rescue).