Vehicle-down Sensor (Service Code 31)
Vehicle-down Sensor Input Voltage Inspection
Be sure the battery is fully charged.
Disconnect the vehicle-down sensor connector and con-
nect the measuring adapter [A] between these connec-
Main Harness [B]
Vehicle-down Sensor [C]
Special Tool - Measuring Adapter: 57001-1700
Connect a digital meter [D] to the measuring adapter
Vehicle-down Sensor Input Voltage
Connections to Adapter:
Digital Meter (+) → R (sensor R/Y) lead
Digital Meter (–) → BK (sensor GY) lead
Refer to the Self-diagnosis Procedures, connect the 12 V
battery to the main harness.
Measure the input voltage with the engine stopped and
with the connector joined.
Standard: DC 4.75 ∼ 5.25 V
If the reading is within the standard, check the output volt-
age (see Vehicle-down Sensor Output Voltage Inspec-
If the reading is out of the standard, remove the ECU and
check the wiring for continuity between the main harness
Disconnect the ECU and sensor connectors.
Wiring Continuity Inspection
ECU Connector [A] ←→
Vehicle-down Sensor Connector [B]
R/Y lead [C] (ECU terminal 12)
GY lead [D] (ECU terminal 17)
If the wring is good, check the ECU for its ground and
power supply (see ECU Power Supply Inspection).
If the ground and power supply are good, replace the ECU
(see ECU Removal/Installation).
FUEL SYSTEM (DFI) 3-53