Replace it if necessary.

Inner Tube Inspection
Spring Tension InspectionRear Brake Pad Installation
Check that the pad spring is in place on the caliper.
Push the caliper piston in as far as it will go.
Install the piston side pad [A] first, and then another pad.
Fit the brake pad end into the recess [B] of the caliper
holder.
Install the pad pin and the plug.
Tighten:
Torque - ...
Drive Chain Slack Inspection
Refer to the Drive Chain Slack Inspection in the Periodic
Maintenance chapter.
Drive Chain Slack Adjustment
Refer to the Drive Chain Slack Adjustment in the Periodic
Maintenance chapter.
Wheel Alignment Inspection/Adjustment
Refer to the Wheel Alignment Inspection in the Periodic
Maintenance ...
Cylinder Head Cover Removal
Remove:
Air Suction Valves (see Air Suction Valve Removal)
Throttle Body Assy (see Throttle Body Assy Removal in
the Fuel System (DFI) chapter)
Stick Coils (see Stick Coil Removal in the Electrical System
chapter)
Remove the clamps [A].
Turn up the front side of the heat insulation ...