2006 ML500 (164.175) with 113.964, 125K miles.

Vehicle is experiencing an intermittent no-start condition, where the ignition key is turned to the crank position and nothing happens - starter remains unactivated and there is no clicking noise typical of low voltage. Two or three repeat attempts at cranking eventually result in normal starter activation, engine cranking and normal running.

The battery is new and load tests at over 850 CCA. Battery terminals and cables are free of corrosion; starter wiring harness is free of corrosion and the mount hardware is secure.

Only evident abnormal finding is when ignition key is turned to position "2", there is a noticeble drop-off in the volume of the door open buzzer and the presence some other in-dash low volume noise that suggests a drop-off in supply voltage. Turning the key to crank at this point results in a no-start condition.

Cycling the key back to position "zero" a few times results in a return to normal warning buzzer volume and subsequent success at cranking.

The no-start condition is now occurring with greater frequency.

Faulty ignition switch?