FUEL SYSTEM (DFI) 3-49

Inlet Air Pressure Sensor #1 (Service Code 12)

Inlet Air Pressure Sensor #1 Removal

CAUTION

Never drop the inlet air pressure sensor #1 especially on a hard surface. Such a shock to the sensor can damage it.

•Remove:

Air Cleaner Housing (see Air Cleaner Housing Removal) Inlet Air Pressure Sensor #1 Connector [A]

•Remove the inlet air pressure sensor #1 [B] from the rubber damper in the bracket [C] and separate the vacuum hose [D].

Inlet Air Pressure Sensor #1 Installation

NOTE

○The inlet air pressure sensor #1 is the same part as the inlet air pressure sensor #2.

•Installation is the reverse of removal.

Inlet Air Pressure Sensor #1 Input Voltage

Inspection

NOTE

○Be sure the battery is fully charged.

•Turn the ignition switch OFF.

•Remove the air cleaner housing (see Air Cleaner Housing Removal).

•Disconnect the inlet air pressure sensor #1 connector and connect the harness adapter [A] between these connectors.

Special Tool - Measuring Adapter: 57001-1700

•Connect a digital meter to the harness adapter leads.

Inlet Air Pressure Sensor #1 Input Voltage Connections to Adapter:

Digital Meter (+) → R (sensor BL) lead Digital Meter (–) → BK (sensor BR/BK) lead

•Measure the input voltage with the engine stopped and with the connector joined.

•Turn the ignition switch ON.

Input Voltage

Standard: DC 4.75 5.25 V

•Turn the ignition switch OFF.

If the reading is within the standard, check the output voltage (see Inlet Air Pressure Sensor #1 Output Voltage Inspection).

3-50 FUEL SYSTEM (DFI)

Inlet Air Pressure Sensor #1 (Service Code 12)

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] ←→

Inlet Air Pressure Sensor #1 Connector [B]

BL lead (ECU terminal 10) [C]

BR/BK lead (ECU terminal 28) [D]

If the wiring 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).

Inlet Air Pressure Sensor #1 Output Voltage Inspection

•Measure the output voltage at the inlet air pressure sensor #1 in the same way as input voltage inspection, note the following.

○Disconnect the inlet air pressure sensor #1 connector and connect the harness adapter [A] between these connectors.

Special Tool - Measuring Adapter: 57001-1700

Inlet Air Pressure Sensor #1 Output Voltage Connections to Adapter:

Digital Meter (+) → W (sensor Y/BL) lead Digital Meter (–) → BK (sensor BR/BK) lead

•Measure the output voltage with the engine stopped and with the connector joined.

•Turn the ignition switch ON.

Output Voltage
Usable Range:	DC 3.80 4.20 V at standard
	atmospheric pressure (101.32 kPa,
	76 cmHg)

NOTE

○The output voltage changes according to local atmospheric pressure.

•Turn the ignition switch OFF.

If the reading is out of the usable range, replace the sensor.

FUEL SYSTEM (DFI) 3-51

Inlet Air Pressure Sensor #1 (Service Code 12)

If the reading is within the usable range, remove the ECU and check the wiring for continuity between main harness connector.

Special Tool - Hand Tester: 57001-1394

○Disconnect the ECU and sensor connectors.

Wiring Continuity Inspection

ECU Connector [A] ←→

Inlet Air Pressure Sensor #1 Connector [B]

Y/BL lead (ECU terminal 8) [C]

BR/BK lead (ECU terminal 28) [D]

If the wiring is good, check the sensor for various vacuum.

•Remove the inlet air pressure sensor #1 [A] and disconnect the vacuum hose from the sensor.

•Connect an auxiliary hose [B] to the inlet air pressure sensor #1.

•Temporarily install the inlet air pressure sensor #1. ○Connect a digital meter [C], vacuum gauge [D], the fork

oil level gauge [E] and the harness adapter to the inlet air pressure sensor #1.

Special Tools - Fork Oil Level Gauge: 57001-1290

Vacuum Gauge: 57001-1369

Measuring Adapter: 57001-1700

Inlet Air Pressure Sensor #1 Output Voltage

Connections to Adapter:

Digital Meter (+) → W (sensor Y/BL) lead

Digital Meter (–) → BK (sensor BR/BK) lead

○Turn the ignition switch ON.

○Measure the inlet air pressure sensor #1 output voltage from various vacuum readings, while pulling the handle of the fork oil level gauge.

○Check the inlet air pressure sensor #1 output voltage, using the following formula and chart.

Suppose:

Pg: Vacuum Pressure (Gauge) of Throttle Body

Pl: Local Atmospheric Pressure (Absolute) measured by a barometer

Pv: Vacuum Pressure (Absolute) of Throttle Body Vv: Sensor Output Voltage (V)

3-52 FUEL SYSTEM (DFI)

Inlet Air Pressure Sensor #1 (Service Code 12)

then

Pv = Pl – Pg

For example, suppose the following data is obtained: Pg = 8 cmHg (Vacuum Gauge Reading)

Pl = 70 cmHg (Barometer Reading) Vv = 3.2 V (Digital Meter Reading)

then

Pv = 70 – 8 = 62 cmHg (Absolute)

Plot this Pv (62 cmHg) at a point [1] on the chart and draw a vertical line through the point. Then, you can get the usable range [2] of the sensor output voltage.

Usable range = 3.08 3.48 V

Plot Vv (3.2 V) on the vertical line. → Point [3].

Results: In the chart, Vv is within the usable range and the sensor is normal.

If the reading is out of the usable range, replace the sensor.

If the reading is within the usable range, 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

Inlet Air Pressure Sensor #1 (Service Code 12)

ID: Idling

Ps: Standard Atmospheric Pressure (Absolute) Pv: Throttle Vacuum Pressure (Absolute)

ST: Standard of Sensor Output Voltage (V) TO: Throttle Full Open

UR: Usable Range of Sensor Output Voltage (V)

Vv: Inlet Air Pressure Sensor #1 Output Voltage (V) (Digital Meter Reading)

3-54 FUEL SYSTEM (DFI)

Inlet Air Pressure Sensor #1 (Service Code 12)

Inlet Air Pressure Sensor #1 Circuit

1.Inlet Air Pressure Sensor #1

2.ECU