Outline
The PCM controls energization to the starter relay according to an immobilizer system request to improve security.
While not in P or N position, the starter relay energization by the ignition key is inhibited. (ATX)
While not in neutral, the starter relay energization by the push button start is inhibited. (MTX)
Block Diagram

Operation
The PCM establishes a ground to the starter circuit. Therefore when the ignition is switched to START, the starter relay is energized and the starter motor rotates. As a result, the engine starts normally.
The PCM does not establish a ground to the starter circuit. Therefore, even if the ignition switch is turned to the start position, the starter motor does not rotate because the starter relay does not energize, and the engine does not start.

The PCM turns the starter relay off with the engine speed at the set value or more (value from engine coolant temperature fluctuates).
Refrigerant Charging
Starter Disassembly/Assembly [Skyactiv G 2.0]Air Intake Actuator Inspection [Full Auto Air Conditioner]
1. Connect battery positive voltage to air intake actuator terminal B (or C),
connect terminal C (or B) to ground, and then verify that the air intake actuator
operates as shown in the table.
If the operation condition is not normal, replace the air intake actuator.
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Quarter Window Glass Removal
1. Disconnect the negative battery cable..
2. Remove the following parts:
a. Trunk board.
b. Trunk end trim.
c. Rear scuff plate.
d. Trunk side trim.
e. D-pillar trim.
f. C-pillar trim.
3. Apply protective tape along the edge of the body and the quarter window glass.
WARNING: ...
Driveline/Axle Features
Improved driveability
Bell-shaped constant velocity joint adopted for wheel-side joint
of front and rear drive shaft
Tripod-shaped constant velocity joint adopted for differential-side
joint of front drive shaft (ATX) and rear drive shaft
...