The headlights shut off and the dash lights change and when you step on the brake pedal. Also the cruise control does not work when the headlights are on.

I researched these codes and found the following suggestions.Has your vehicle gone into limp mode (i.e.-check engine light is on &/or vehicle isn't making its normal power output??) Check your transmission fluid with the engine warm and at idle and if it's low,fill it to the appropriate level.P0700 is normally set when the tcm detects a fault.This is a common fault code in this model.Low/dirty transmission fluid can cause two sensors inside the transmission to short out requiring you to replace them.P0571 is related to the brake/cruise control switch, which is connected to your brake pedal.This operates your brake lights and deactivates the cruise control when you step on the brake pedal to slow down/stop.Have someone verify your brake lights are working and also make sure they're not remaining on after the pedal is released as non functioning brake lights could cause an accident.If your cruise control is working,verify it is shutting off when you press the brake pedal down.If it's not shutting off,that could also be dangerous too just like no brake lights.If it's not shutting off,check the switch to make sure it hasn't been knocked loose from the pedal and check the wiring harness also to make sure it's still connected.Check any fuse for the cruise control and brake lights also.
If the transmission fluid is low and you top it off and if you correct any condition present with the cruise/brake light switch,clear the codes with a scanner or get AutoZone/Etc to do it for free to see if the codes clear and remain that way.

Cars these days have electronic switches connected to the computer system, and they operate simply, until a little glitch shows up. In my case, the brake switch plunger strike pad had disintegrated. This little half inch button goes into a metal pad that presses against the brake switch when the brake is released. The cruise control operates the same, both activated by the brake pedal, both found under the dash. If not this, the switch might be bad. Both found at Advance Auto.

which make of car and year search finds you the part

are you up to DIY and purchase of parts fitting new parts

its sensors near the top of the brake pedal under the dash

P0571 Cruise Control/Brake Switch A Circuit Malfunction
P0573 - Cruise Control/Brake Switch A Circuit High

C107C - Brake Pedal swithch 1/2 Stuck
C107D -brake pedal switch 1/2 correlation

some examples of locations cruise/brake switch

This sounds like the brake light switch or the control switch on the brake pedal is bad or loose. Check under the dash above the brake pedal there should be one or two switches that tell the brake lights to come on and the cruise control to shut down.

brake pedal and clutch pedal movements are very sensitive for a cruise control so any movement of the pedal will cancel the cruise setting.

hi poss one or both brake light bulbs filaments are touching causing a back feed note if the brake lights are on the cruise control is cancelled

You have a defective cruise/brake light switch (pedal activated)

Here is some information to consider and check. You should concentrate on the taillights first since that does not require you to constantly step on the brake pedal.

The bulb outage module, or lamp outage module, is located to the left of the drivers left leg while sitting in the seat. It is just slightly up under the dash, clipped into a black housing. It should be a white colored box with one large electrical plug with many wires plugging into it.

The switch above the brake light switch should be a cruise control deactivation switch, so that the cruise control turns off when the brake pedal is pressed.

Sounds to me like you may have a instrument cluster problem.

Try pulling the brake pedal up with your toe and setting the cruise control while you hold it up with your toe. If it engages, stop holding the brake pedal up. It will either disengage immediately or after you hit a bump. Or if you step on the brake, of course.

There's a brake pedal sensor button on the steering column right where the brake pedal arm intersects it. I put a self]adhesive felt pad (buy at wal-mart, home depot, etc) on the pedal arm where it makes contact with the sensor button. Fixed. Been working fine for a year now.

Gene C