My son-in-law’s 325i BMW has been in our driveway for weeks. one night i saw the brake lights, tail lights and back-up lights blinking on and off erratically. this went on randomly for a while. now the car won’t start. the engine won’t turn over when jumped, either. i suspect there is a short somewhere.
what do you think?
I think I’d start by fully charging the battery with a charger. Disconnect the negative battery cable when you do this in case there is a power drain present in the car. Then I’d check all the fuses and fusible links if the car still won’t start. If you can get it started, then I’d check the alternator for proper output.
It may be the battery got so low that the alarm system was acting erratically and flashing the lights—not sure if all the lights you mentioned would be involved.
Oh, and you mentioned that it won’t “turn over” even with a jump. Do you mean that the starter will not crank the engine, or that the engine will crank but not “catch”? And if it will not crank, do any lights at all come on when you turn the key? Do the radio, headlights, etc. still work?