Because the wiring in vehicles is all wrapped up in bundles and frequently inaccessible
, it is a WHOLE lot easier to troubleshoot electrical problems using a factory electrical manual.
Sometimes this is a separate book from the factory service manual. Sometimes it is a part of the factory service manual set of 3 or 4 books. These show everything on the circuit including relays, show fuses and what all is on each circuit or which fuses are for a particular circuit, locations of wiring, locations of connectors and devices, and wire colors and pin outs for connectors.
You can order a factory service manual set which should include the wiring diagrams from your dealer or here... http://www.helminc.com