Alternator/Starter motor issues

[Enoch]

I assume you disconnected the battery before replacing the alternator? Double check your connectors, especially any earths that you may have disturbed. Check you are getting about 14 volts across the battery when the engine is running. Rangies can be a real pain for setting codes, especially if it's a P38 - quite often you have to reset all the electric windows and the sunroof after a battery disconnect. You will most likely need to clear teh fault code via a code reader.