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 InspectionCylinder Head Removal
Remove:
Thermostat Housing (see Thermostat Removal in the
Cooling System chapter)
Exhaust Pipe (see Exhaust Pipe Removal)
Camshafts (see Camshaft Removal)
Heat Insulation Plate [A] (see Engine Removal in the
Engine Removal/Installation chapter)
Place a container under the coolant dr ...
Commutator Cleaning and Inspection
Clean the metallic debris off the between commutator
segments [A].
NOTE
Do not use emery or sand paper on the commutator.
Check the commutator for damage or abnormal wear.
Replace the starter motor with a new one if there is any
damage or wear.
Visually inspect the commutato ...
Lower Crankcase Assembly
Install the ball bearing [A] and the oil level inspection window
[B] until they are bottomed
Apply soap and water solution to the oil level inspection
window before installation.
Install the new circlip [C].
Apply a non-permanent locking agent to the oil passage
plug [D].
Tighten: ...