* The vehicle owner's manual: The owner's manual for your G20 van should include a wiring diagram.
* Online resources: There are a number of websites that offer wiring diagrams for vehicles, including Chevy G20 vans. Some popular sites include:
* [Wiringschematic.com](https://wiringschematic.com/)
* [AutoZone.com](https://www.autozone.com/)
* [AdvanceAutoParts.com](https://www.advanceautoparts.com/)
* Parts stores: Some auto parts stores may also sell wiring diagrams for vehicles, including Chevy G20 vans.
When looking for a wiring diagram, be sure to have the following information on hand:
* Vehicle year, make, and model: The diagram you find should be for a 1987 Chevy G20 van.
* Trim level: If available, the diagram should also be for the specific trim level of your G20 van.
* Engine type: The diagram should also be for the engine type in your G20 van.
Once you have located the appropriate wiring diagram, be sure to read and follow the instructions carefully before attempting to make any changes to your vehicle's electrical system. If you are not comfortable making these changes yourself, you can have the work done by a qualified automotive technician.
