It is possible to determine the starter wiring terminals for troubleshooting the starter in M54 engine. It is advisable that you check the state of charge of your battery, inspect wires, terminals and ground connections for good contact and clean tight ground connections between the battery, body, and engine to have a slow turning starter from START position. If no faults are found, replace the starter. In case of failure of this system to operate properly or at all, it is better to check EWS (drive-away protection system) and try another ignition key. But if no defects are detected in these two cases then through BMW scan tool equipment EWS system has to be checked on. Also, checking gear position switch is essential here. There's no separate neutral safety switch; instead automatic transmission range switch (gear position switch) signals EWS system which disables start process when gears other than PARK or NEUTRAL are selected. At terminal 50 of starter motor with key in START position we can test for battery voltage by checking wiring between ignition switch and starter terminal as well as check for any faults within EWS system or other inputs that may disrupt power at terminal 50 towards the starter motor. The issue might be inside the starter motor when voltage exists and there are no visible wiring faults elsewhere. Removing and installing a Starter in M54 Engine involves following steps: first disconnect negative (-) battery cable; secondly raise vehicle safely supporting it;. Remove lines and vacuum components beneath intake manifold required to access starter., also remove the heat shield if so equipped from the starter under intake manifold.. Underneath disconnect positive (+) lead of battery from start ensuring its routing path is noted down as per illustration below it.. After removing transmission bolts securing it to bell housing/engine block, use long extension plus universal joint at output end of transaxle remover fastenings attaching it into unit itself.Completely out carefully via bell housing followed by remaining harness bring down . Finally, remove the starter from below and check the starter pinion gear and flywheel teeth for damage. The new starter is then installed in exact reverse order. When dealing with N52 engine, for removing and installing a Starter it's necessary to disconnect negative (-) battery cable as well as cover the battery terminal to avoid accidental contact with anyone/everything.. Work at the electrical connections of the starter solenoid after removal of engine air filter housing and ducts, ignition coil cover, intake manifold (without detaching fuel lines or injectors). Taking out fastener unscrew B+ wire from solenoid by using wire clip which is pressed in release position. The aluminum bolts (which may not always be marked with blue paint) are removed while lifting out the starter motor.. Before installing new starters turn over engine examining gear teeth through hole of starting hole to replace if they are damaged. At last return back the starting system and refit all terminals that were removed previously.. First remove the starter following described previously so that solenoid switch could later be removed or installed again. Disconnect field winding strap between starter motor and solenoid switch.. In case if field winding strap is damaged or burned buy a new/rebuilt starter motor. Take off solenoid switch mounting screws separating it from the starter pulling them apart until lever on drive receives plunger.. Installation of this kind has a reverse pattern excepting for putting light grease on solenoid piston and adjusting field winding strap not touching body of start as recommended solutions for these points respectively.