I have a Ml500 during the week it started to turn over slowly like the bat was going. Today my wife got stuck it would not start. I jumped it . Started up . Thinking it was the bat I drove to PeP boys for a new one ( they were the only place that had one) . They checked the bat and said it was charged . Tried to jump it nothing but dash lights. Is their a fuse ? I think the one at the bat is ok. Help ( never bring your ML to Pep Boys.

 

Is your engine cranking, just not firing?
Fuel delivery problem (check fuel pump relay, fuel pump or bad check valve in the filter assembly).
Clicking noise from starter?
Starter solenoid or worn down power contacts inside the starter unable to make good enough connection between positive battery cable and starter motor windings.
No noise, only dash lights?
I would check all battery connections, wiring inside of fuse box under the starter relay wires may not have good connection with relay or bad connection at the starter solenoid. Also check if the security diode will blink for half of a second when you turn on your in the ignition switch. Be careful jump starting your ML, you could do more damage to electronic parts then you could think off!
Good luck,
Bernard

 

try put your negative jump lead from the battery to the engine.had one before that had engine earth lead broke,ran a new one from the bulkhead to engine and that sorted it.very same symptoms as yours.

 

Thanks . Ended towing it to the dealer it was the starter $730.00 och.