Sorry bro, I used the abbreviation for it, some times too much.

CHMSL = Center High Mount Stop Lamp / aka 3rd brake light. This is the same place the cargo lamps are at on the top back of the cab ( I know, too little to thank you captain obvious )

If the connector C238 is in the same place on the 2009, that is dirt easy to find it.

Take a look at this in the technical articles / how-to forum

https://www.f150online.com/forums/ar...t-circuit.html

This was written using a 2006 MY truck, but worth a look to see if it is the same on your 2009.

Body parts might come off a bit different, but the thread shows easy access to tap into the circuit ( again watch the load on this circuit ) and get out of the cab of the truck using the factory wire routing.

Keep in mind, the wire color changed from the 04-08 to 2009 MY trucks, as well as the pin placement in C238 could be different.

Sorry have not seen a 2009 up close to know if the wire access is the same, I am taking a SWAG here.

 

Thanks much for your help. After rethinking how I wanted it to operate, I ultimately spliced into the running lights wire [brown] going to the trailer connection. I connected to the lights through an illuminated waterproof toggle switch mounted behind the tailgate latching pin on the driver's side. A bed cover keeps this area dry most of the time and the switch is well protected by the tailgate when it is up or the latching pin when it is down.