P0571 Mazda -

Question

I installed two bumper lights (from CorkSport) in May 2013 on my Mazda3 2012 Skyactive 2.0L and connected them to the parking/brake lights (connections were soldered). Here is the problem: if the car has been parked for a few hours, say overnight, if the parking /headlights are turned on in the morning, I see the brake lights come one in the rear (even though I am not stepping on the brake pedal!). If the lights are turned on without the engine running, the brake lights will stay on for 2 minutes, then go out and I only have the parking lights on (as it should be to begin with). If I do turn the engine on and drive, the brake lights will go out within 40-50 yards (in less than 2 minutes) and after that the parking/headlights, brake lights and cruise operate as expected and will continue to operate even if the car is parked for an hour or two ( i.e. the brake lights will come on only when I step on the brake pedal and I am only mentioning cruise because of what I've read on some blogs. I have not had any issues with cruise). This situation occurs only if the car has been parked for long periods (not sure how long, sometimes it happens after a couple hours and sometimes it doesn't happen after 4-5 hours; but it always happens after it's been parked over night). The Check Engine Light has come on only twice in the last 4 months (since installation) and both times it did not re-appear after I stopped and restarted the engine; however, I did check and got error code P0571 which has something to do with the brake light switch. CorkSport say they have never heard of such issue. Could the brake switch be faulty? Or maybe the computer doesn't know that additional lights have been installed? The car was bought new and now has a little over 9,000 miles. The lights operate fine once the initial malfunction goes away. I'm kinda used to the situation now but I would still appreciate any input or suggestions from anyone more knowledgeable. Thanks!