There is a slight issue with the Continental Ate ABS systems used in the Nissan Frontier and Xterra. A portion of the analog control block and serial data port fails internally, causing intermittent ABS codes to appear even though sensors etc are okay. Usually LF wheel sensor or pump motor codes appear at first. Eventually all communication with ABS controller to drivetrain computer will be lost.
The Continental ABS controller can be repaired for much less than the $1100.00 part cost.
Installing a stereo, even jumpstarting vehicle with two batteries in series (24V) WILL NOT cause damage to the ABS controller as all electronic systems in the vehicle are designed to withstand 50 volt power surges sustained for minutes if not indefinitely.