Pcm Removal/Installation

Disconnect the negative battery cable.
Disconnect the connector from the PCM installed on the upper part of the brake pedal.
Remove the bolt and nut holding the PCM.

Fig 1: Locating PCM Installation Bolt
Courtesy of MAZDA MOTORS CORP.
1. Push the harness (PCM harness) installed to the brake pedal bracket in the opposite direction of the brake pedal bracket.
2. While pushing the harness, push the stay until it comes apart from the stud with the PCM installation nut.
  
  Fig 2: Removing PCM Wiring Harness
  Courtesy of MAZDA MOTORS CORP.
3. Remove the PCM installation nut.
Install in the reverse order of removal.
Tightening torque
1. Bolt, nut: 7.9-10.7 N.m {80-110 kgf.cm, 70-95.4 in.lbf}
Fig 3: Tightening PCM Installation Nut
Courtesy of MAZDA MOTORS CORP.