With Position Memory System: Outline

WARNING: This page is about a different car, the 2020 Mazda CX-30. However, it is still accessible from the selected car via links, so may be relevant.

DTC B1520:87 [DASH-ELECTRICAL SUPPLY UNIT] DETECTION CONDITION AND POSSIBLE CAUSE

System malfunction location	Communication error with seat warmer control unit/position memory control module
Detection condition	The dash-electrical supply unit cannot receive the signals from the seat warmer control unit/position memory control module.
Fail-safe	Stops the driver and front passenger's seat warmer output. Inhibits the seat position recall and seat position programming of the position memory system.
Possible cause	Seat warmer control unit/position memory control module connector or terminal malfunction Dash-electrical supply unit connector or terminals malfunction Short to ground in seat warmer control unit/position memory control module LIN communication line Short to power supply in seat warmer control unit/position memory control module LIN communication line Open circuit in seat warmer control unit/position memory control module LIN communication line Seat warmer control unit/position memory control module malfunction Dash-electrical supply unit malfunction
Courtesy of MAZDA MOTORS CORP.