Here are some places to look:
* Repair Manuals: A Haynes or Chilton repair manual specific to your year and model GMC 2500 will contain detailed wiring diagrams. These are available at most auto parts stores and online retailers. These are usually your best bet for a complete and accurate diagram.
* Online Automotive Parts Websites: Websites like AutoZone, Advance Auto Parts, and Napa Auto Parts often have online parts catalogs. While they primarily focus on parts, some allow you to access wiring diagrams (sometimes for free, sometimes for a fee or requiring an account). Search for your specific vehicle's year, make, and model.
* GM's Website (Possibly): GM might have some limited information available on their website, but accessing complete wiring diagrams directly from them is usually not possible without a dealership subscription.
* Dealership: Your local GMC dealership is the most likely place to find the most comprehensive diagrams, but they might charge a fee for access or copies.
* Online Forums: Forums dedicated to GMC trucks (e.g., GMC Sierra forums) might have members who have shared wiring diagrams or can point you in the right direction. However, always double-check the reliability of information found on forums.
Important Note: When working with electrical systems, always disconnect the negative battery terminal before starting any work to prevent accidental shorts or damage. Incorrect wiring can lead to vehicle damage or injury. If you're not comfortable working with automotive electrical systems, it's best to consult a qualified mechanic.
