Here's a weird one......... Had a 550 that just had a battery drain itself while parked at an airport. Recovered car and fitted new battery and new alarm siren too (very old type, irrepairably corroded inside)..... Fuel pump with strike through it symbol (inertia failure NOT the low fuel level)on warning display panel, and indicators flash erratically and non symmetrically (RH super fast and dim). Car starts and runs fine. Turns out the Fuel pump inertia switch had an internal back feed, causing the problem. New switch was about AUD$55, and an hour at the dealer (as I wasted an hour and gave up) on the SD1 to diagnose and fix it.