The following electrical troubleshooting and wiring diagram manual applies for BMW L6/M6 1987 model year. This manual will show you the entire electrical schematics of the vehicle in a manner that makes troubleshooting easier. Electrical components which work together are shown together on one schematic. Within the schematic, all switches and sensors are shown “at rest”.
Isolating the electrical problems: make circuit tests to prove or disprove the preliminary diagnostic; keep in mind that a logical simple procedure is the key to efficient troubleshooting; test for the most likely cause of failure first.