From The E28 Wiki

Car Won't Start

By Lotus72D, Tue Jan 31, 2006

Original thread: Car Won't Start

Problem: Car Won't Start

Solution Contained Here: [1]

Get the electrical diagrams from this [2], if needed. These diagrams, in the Electrical Troubleshooting Manual (ETM) show the wiring colors as well as the pin outs for most of the car. It also has pictures of the components, lists their locations and has splice and ground information. Get the one for your car and put it on your computer. Print out the pages you need, then post questions in a new thread.

ETM Link: [3]