I have a 2006 Silverado which has a factory plug for the brake controller in the main wiring harness connector box, next to the steering column.
The 2007 does not have the factory plug but it does have a brake controller wire harness bundle under the dash, near the steering column. The wires are color coded the same as the wires that come with the new brake controller. I highly recommend the Prodigy. All you have to do is splice the wires together with the same color wires that come with the brake controller. So easy......a cave man can do it......
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Check out this video......the '09 is the same as your '07.
The others are correct about just installing the fuse for the charging circuit.