I dont know if this will help anyone but I found in the chiltons manunal that all models 89-95 E30 and E36, have a self diagnostic on board system that will pull trouble codes for on the das with the check engine light. Its like a " flash "
numbering system, start by turning ignition switch to on positon, engine not running, press accelerator pedal to the floor 5 times within 5 seconds, check ...