*Your truck MUST be pre-wired for the CLN25 Circuit and GD406 Circuit in order for this adapter to provide power to your accessories. All trucks equipped with the Trailer Assist Lamp, as well as most trucks with a factory-installed tow package are pre-wired. To determine if your truck is pre-wired, check the C431 inline connector. On at least one of the plugs, Pin #6 (Black with Yellow Stripe) and Pin #7 (White with Green Stripe) must both be present for this adapter to work. If they are not, you will also need Starkey #4572 Power Extension Wiring.