Possible cause
WARNING: This page is about a different car, the 2009 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.
- Connector terminal disconnection, poor contact, damage, deformation, corrosion
- Open circuit in wiring harness between ABS/TCS HU/CM and branch A
- ABS/TCS HU/CM malfunction
Courtesy of MAZDA MOTORS CORP.