Special Tool - Measuring Adapter: 57001-1700
Main Harness [B] Vehicle-down Sensor [C]

Vehicle-down Sensor Output Voltage Connections to Adapter: Digital Meter (+) → W (sensor Y/G) lead Digital Meter (–) → BK (sensor BR/BK) lead

70° or
Output Voltage
Standard: With sensor tilted 60
70° or more right or
left: DC 0.65
1.35 V
With sensor arrow mark pointed up: DC
3.55
4.45 V
If the reading is out of the standard, replace the sensor.

If the reading is within 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] Y/G lead (ECU terminal 38) [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 Circuit

1. ECU
2. Vehicle-down Sensor
Vehicle-down Sensor Input Voltage Inspection
Subthrottle Sensor (Service Code 32)Exhaust System Identification
Exhaust Pipe Mark Position [A]
Premuffler Chamber Mark Position [A]
Muffler Body Mark Position [A]
Premuffler Chamber [A] with Hole [B] for Oxygen Sensor [C]
Honeycomb Type Catalyst Position [A]
Specifications
...
Brake Fluid Level Inspection
Check that the brake fluid level in the front brake reservoir
[A] is above the lower level line [B].
NOTE
Hold the reservoir horizontal by turning the handlebar
when checking brake fluid level.
If the fluid level is lower than the lower level line, fill the
reservoir to the upper lev ...
Subthrottle Valve Actuator Inspection
NOTE
Be sure the battery is fully charged.
Remove the air cleaner housing (see Air Cleaner Housing
Removal in the Fuel System (DFI) chapter).
Turn the ignition switch to ON.
Check to see that all the subthrottle valves [A] open and
close smoothly.
Turn the ignition switch to OFF.
I ...