NOTE
Be sure the battery is fully charged.
Main Harness [B] Vehicle-down Sensor [C]
Special Tool - Measuring Adapter: 57001-1700

Vehicle-down Sensor Input Voltage Connections to Adapter: Digital Meter (+) → R (sensor BL) lead Digital Meter (–) → BK (sensor BR/BK) lead

Input Voltage
Standard: DC 4.75
5.25 V
If the reading is within the standard, check the output voltage (see Vehicle-down Sensor Output Voltage Inspection).
If the reading is out of the standard, remove the ECU and check the wiring for continuity between main harness connectors.
Special Tool - Hand Tester: 57001-1394
Disconnect the ECU and sensor connectors.
Wiring Continuity Inspection ECU Connector [A] ←→ Vehicle-down Sensor Connector [B] BL lead (ECU terminal 9) [C] BR/BK lead (ECU terminal 13) [D]

If the wiring is good, check the ECU for its ground and power supply (see ECU Power Supply Inspection in the Fuel System (DFI) chapter).
If the ground and power supply are good, replace the ECU (see ECU Removal/Installation in the Fuel System (DFI) chapter).
Vehicle-down Sensor Installation
Vehicle-down Sensor Output Voltage InspectionSubthrottle Sensor Resistance Inspection
Turn the ignition switch to OFF.
Disconnect the subthrottle sensor connector.
Connect a digital meter [A] to the subthrottle sensor connector
[B].
Measure the subthrottle sensor resistance.
Subthrottle Sensor Resistance
Connections: BL lead [D] ←→ BR/BK lead [C]
Standard: ...
Balance Inspection
Remove the front and rear wheels (see Front/Rear Wheel
Removal).
Support the wheel so that it can be spun freely.
Spin the wheel lightly, and mark [A] the wheel at the top
when the wheel stops.
Repeat this procedure several times. If the wheel stops
of its own accord in various positi ...
Balancer Installation
Position the crankshaft at #2, 3 positions TDC or at #1, 4
positions TDC.
Install the balancer assembly as follows.
Align the punch mark [A] on the weight and the projection
[B] on the crankcase.
Engage the balancer gear and the crankshaft gear.
Insert the balancer shaft until it is bot ...