Wave Profile Inspection

Remove the PCM. See PCM REMOVAL/INSTALLATION .
Connect WDS or equivalent to DLC-2 connector.
Connect oscilloscope test leads to the following PCM connector terminals.
- (+) lead: PCM terminal 3V
- (-) lead: PCM terminal 4A
Fig 1: Identifying PCM Harness Side Connectors (24 Pin & 31 Pin)
Courtesy of MAZDA MOTORS CORP.
Start the engine.
Monitor RPM PID.
Inspect wave profile when idling engine.
- If wave profile or voltage are out of specifications, carry out the "Circuit Open/Short Inspection". See CIRCUIT OPEN/SHORT INSPECTION .
  - PCM terminal: 3V(+) <-> 4A(-)
  - Oscilloscope setting: 2.0V/DIV(Y), 20ms/ DIV(X), DC range
  - Vehicle condition: Idling
  Fig 2: Identifying Wave Profile Of PCM
  Courtesy of MAZDA MOTORS CORP.