1985 280SL Ignition Failure Cause?
 

I recently purchased a non running 280SL. Its turned out to be the Coil & Ignition Control Unit were bad. At 1st, only the coil was bad, then after a short test ride, the Ignition Control Unit failed too( luckily just after returning to driveway). I've replaced both parts, after doing a spark test & following tests in the Haynes manual. Voltage at battery while running is at 13 volts. Is there something else probably wrong that I should be checking for, that might burn-up the new Coil & Ignition Control Unit? Or is this just an unusual case? My 280TE still has its original Coil & ICU after 370k miles

Most likely caused by build-up of excessive resistance in the secondary ignition system.

IN other words. Bad wires cap, rotor, & or coil.