GM Wiring Diagrams and Pinouts Download Wiring Diagrams and Pinouts. Below is a list of GM wiring diagrams and pinouts I currently have available for download. Some of these are ADOBE Acrobat . pdf format files in a compressed folder. You will need to unzip these files and open them with adobe reader. Free Auto Repair Diagrams - FreeAutoMechanic Free Auto Repair Diagrams Below we provide access to three basic types of diagrams that will help in the troubleshooting and diagnosis of an automotive related problem. Wiring diagrams are one of the most common these days with all the added electronics.