To find the correct wire, you must consult your vehicle's wiring diagram. This diagram will show the wire color(s) for the brake light circuit at the switch. You might find a wire labeled directly as a brake light circuit, or it might be part of a larger bundle.
How to find the wiring diagram:
* Online Resources: Search online for "2009 Ford Ranger wiring diagram" specifying your engine size and trim level if possible. Several websites offer free or paid access to wiring diagrams. Be cautious of the source and verify its reliability.
* Ford Dealership: A Ford dealership service department will have the factory wiring diagrams. They might charge a small fee for a copy.
* Repair Manual: A Haynes or Chilton repair manual for your specific vehicle should also include the wiring diagrams.
Important Safety Note: Incorrect wiring can lead to brake failure. If you are not comfortable working with vehicle wiring, have a qualified mechanic install your brake controller. Using a multimeter to test the circuit is crucial to ensure you have the correct wire before connecting the brake controller.
