If the connector is clogged with mud or dust, blow it off with compressed air.
If the terminals of the main harness connectors are damaged, replace the main harness.
If the terminals of the ECU connectors are damaged, replace the ECU.

Gray Connector [A]

Special Tool - Hand Tester: 57001-1394
ECU Grounding Inspection
Connections:
(I) BK/Y leads (ECU terminal 40, 73 or 74) ←→ Battery (–) Terminal
(II) Engine Ground ←→ Battery (–) Terminal
Criteria: Both: 0 Ω
If no continuity, check the connectors, the engine ground lead, or main harness, and repair or replace them if necessary.
If the wiring is good, check the power source voltage of the ECU.

NOTE
Be sure the battery is fully charged.
Special Tool - Needle Adapter Set: 57001-1457
ECU Power Supply Inspection Connections:
(I) Digital Meter (+) → Terminal 41 (W/BK)
Digital Meter (–) → Battery (–) terminal
(II) Digital Meter (+) → Terminal 53 (BR/W)
Digital Meter (–) → Battery (–) terminal
(III) Digital Meter (+) → Terminal 54 (W/BK)
Digital Meter (–) → Battery (–) terminal
Ignition Switch OFF:
Terminal 41 (W/BK): Battery Voltage
Terminal 53 (BR/W): 0 V
Terminal 54 (W/BK): Battery Voltage
Ignition Switch ON:
All: Battery Voltage
If the reading is out of the specification, check the following.
Main Fuse 30 A (see Fuse Inspection in the Electrical System chapter)
ECU Fuse 15 A (see Fuse Inspection in the Electrical System chapter)
ECU Main Relay (see Relay Circuit Inspection in the Electrical System chapter)
Power Source Wiring (see wiring diagram in this section)
If the fuse, wiring and relay are good, replace the ECU (see ECU Removal/Installation).
ECU Removal
ECU Power Source CircuitTire Air Pressure Inspection
Remove the air valve cap.
Measure the tire air pressure with an air pressure gauge
[A] when the tires are cold (that is, when the motorcycle
has not been ridden more than a mile during the past 3
hours).
Install the air valve cap.
Adjust the tire air pressure according to the specifi ...
Ignition Switch Replacement
Remove:
Air Cleaner Housing (see Air Cleaner Housing Removal
in the Fuel System (DFI) chapter)
Disconnect the lead connectors [A].
Remove:
Steering Stem Head (see Stem, Stem Bearing Removal
in the Steering chapter)
Using a small chisel or punch [A], turn out the Torx bolts.
...
Steering Stem Warp Inspection
Whenever the steering stem is removed, or if the steering
can not be adjusted for smooth action, check the steering
stem for straightness.
If the steering stem [A] is bent, replace the steering stem.
Stem Cap Deterioration, Damage Inspection
Replace the stem cap if its oil seal [A] s ...