need help, advanced advice please.
 

okay just bought a 1991 525i 5speed, here is whats going on so far:

random flashing check engine light, w/ slight misfire
code1231
surging / pulsing headlights, and interior lights

okay so based on whats known the code 1231, i wanted to check the alternator and voltage at pin 26 of the dme control unit.

now my question is, where is the dme relay, the dme control unit, and how difficult is the r&r process for the alternator? (any special tools needed?)

thank you in advance guys...