BMW E46 Alternator Fault and Replacement
E46 charge light on: how do you confirm an alternator fault?
Measure the battery terminal voltage with the engine running. It should be about 13.6 V or more. If the voltage is clearly lower, the fault is in the charging system. Also check the belt and the tensioner pulley, as a seized pulley can cause whining and the charge light to come on.
Is replacing the E46 alternator brushes enough?
Often it is, if the slip rings are in good condition. If the grooves in the ring are deep, the brushes alone may not be enough. The brushes and the voltage regulator can also be replaced as one package. The brushes of a Valeo alternator have run out on many 320d cars before 350,000 km.
How do you remove the alternator on the E46 320d (M47N)?
1. Disconnect the battery lead first. 2. Take off the engine covers and the upper end of the intake pipe. 3. Remove the power steering pump's three screws and move it aside without disconnecting the hoses. 4. Loosen and remove the serpentine belt. 5. Disconnect the wires and remove the alternator's two screws.
Does an alternator of a different size fit the E46?
An alternator of a different size may require programming of the engine control unit. The Bosch 140 A alternator of the E39 523i (1998) fits the E46 325ti (M54B25) directly. The 120 A and 150 A alternators differ in pulley, so check the pulley before replacing.