We will start with the pdf manual. http://a248.e.akamai.net/pix.crutchfield.com/Manuals/130/130P5200HD.PDF
Next you will check all the speaker connection's so they are biased +- +-. Ensure your ground is correct at the chassis of the receiver to the frame of the car.
Here is the manual from Manual Labs another look. Pioneer DEH P5200 Manual
There is a reset on the speaker output located in the manual. Perhaps your speaker impedance is above the receivers digital tolerance. Bench test the speakers with other in place of the working site. Most of all situations are oversights or happenings when closing up the job site.
Audio adjustments at your finger tips to check that by the book.
Pioneer DEH P4800MP Operation Manual Page 25 Using Balance Adjustment
And finally. Our site has a lot of answers. Please take some more time to familiarize your head with it. After doing some trouble shooting from a-Z check this out.
Troubleshooting Support for Pioneer DEH P5200 CD Player
Everyone please learn the ropes at Fix Ya. A lot of your answers may be posted. Please take patience into account for those who strive to prepare their sincere intentions to succeed.
Please? We want you to rock. Easy does it.