* Online Automotive Repair Manuals: Websites like Haynes.com and ChiltonDIY.com offer repair manuals (often available for purchase) that include detailed wiring diagrams. These are generally considered good quality and quite comprehensive.
* Factory Service Manuals: These are the most comprehensive manuals, directly from GMC (or a GM dealership). They are usually more expensive than Haynes or Chilton but offer the most detailed and accurate information. You can sometimes find them used online through sites like eBay.
* Online Forums and Communities: Websites and forums dedicated to GMC Sierra trucks (like some dedicated to classic trucks or specific years) often have members who share wiring diagrams or have discussions about specific wiring issues. Be cautious; information found here is user-generated and accuracy varies.
* Auto Parts Stores: Some larger auto parts stores (like AutoZone or Advance Auto Parts) may have access to wiring diagrams through their computer systems, though this is not guaranteed for all years and models.
When searching, be very specific. Include the year (1997), make (GMC), model (Sierra), and engine size (e.g., "1997 GMC Sierra 5.7L Wiring Diagram") to get the most accurate results. Also specify what part of the wiring diagram you need if possible (e.g., "1997 GMC Sierra 5.7L headlight wiring diagram").
Remember to always disconnect the negative battery terminal before working with any vehicle's electrical system to prevent shorts or damage.
