Electricity is something not many people understand. Some call it voodoo, some call it magic, but if you are going to be a good automotive mechanic, it is important you know the basics and how to read an electrical schematic (diagram). I can’t tell you how many times a day I get messages from customers asking me about electrical issues in their car. If you do not fully understand how it works, it can even be dangerous to work on, so please ask questions before touching the wiring system in you car.
If you have been following Race German for a while, you know that I went to school for aircraft maintenance. I obtained my FAA Airframe and Powerplant license in 2010 (A&P). In A&P school, we had almost a year of schooling just on electrical systems, how they worked, and how to troubleshoot. Even though it’s not always the most fun subject, it was one of the most important lessons I learned in school.
Swapping engines is not anything new in the BMW world. With all of the information on the internet, many younger mechanics are now 24V swapping engines in their E30, or V8 swapping engines in their E36. The biggest mistake that I see from most people is overly trusting the internet on wiring. There are many DIY write ups on the wiring for these swaps. The problem is, all BMW models are not the same. BMW changed a lot of their wiring throughout the years. It is very dangerous to trust someones wiring diagrams without double checking for yourself. Make sure you do a pinout on every wire in the harness so you know it is going to the correct spot.
Luckily, there was a kind person that uploaded all of the OEM BMW wiring troubleshooting guides and schematics on the internet. These PDF files are the lifeline to any good automotive technician. Check out the link below, and find your car. I would even suggest you download the pdf and keep a copy on your computer.
As I stated above, electricity is no joke and can cause much damage to your vehicle if you are not careful. If you are ever unsure ask before splicing into a circuit.