Inlet Air Pressure Sensor Output Voltage Inspection note

○^{The output voltage changes according to the local at-}

mospheric pressure.

_• Measure the output voltage at the ECU in the same way as input voltage inspection. Note the following.

Inlet Air Pressure Sensor Output Voltage Connections to ecu

Meter (+) → Y/BL lead (terminal 8) Meter (–) → BR/BK lead (terminal 28)

Usable Range: 3.74  4.26 V DC at the standard

atmospheric pressure (101.32 kPa, 76 cmHg abs.)

_• Turn the ignition switch OFF.

If the output voltage is within the usable range, check the

ECU for its ground, and power supply (see ECU Power Supply Inspection).

If the output voltage is out of the usable range, remove the fuel tank and check the wiring. If the output voltage is

4.8 V, the ECU is normal.

If the wiring is good, check the sensor for various vacuum. If the output voltage for various vacuum is normal, check the ECU for its ground, and power supply (see ECU Power Supply Inspection).

_• Remove the inlet air pressure sensor [A] and disconnect

the vacuum hose from the sensor.

○^{Do not disconnect the sensor connector.}

_• Connect an auxiliary hose [B] to the inlet air pressure sen- sor.

_• Temporarily install the inlet air pressure sensor.

○^{Connect a commercially available digital meter [C], vac-}

uum gauge [D], the fork oil level gauge [E] and the har-

ness adapter to the inlet air pressure sensor.

Special Tools - Fork Oil Level Gauge: 57001-1290

Sensor Harness Adapter: 57001-1561

Inlet Air Pressure Sensor Output Voltage Connection to Adapter

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

○^{Turn the ignition switch ON.}

○^{Measure the inlet air pressure sensor output voltage from various vacuum readings, while pulling}

the handle of the fork oil level gauge.

○^{Check the inlet air pressure sensor output voltage, using the following formula and chart.}

Suppose:

Pg: Vacuum Pressure (gauge) to Sensor

Pl: Local Atmospheric Pressure (absolute) measured by a barometer Pv: Vacuum Pressure (absolute) to Sensor

Vv: Sensor Output Voltage (V)

then

Pv = Pl – Pg

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

Pl = 70 cmHg (Varometer reading) Vv = 3.2 V (Digital volt meter reading)

then

Pv = 70 – 8 = 62 cmHg (Abs.)

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 = 3.04  3.49 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.

Pv = 24  55 cmHg

Pv = 55  86 cmHg

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 Output Voltage (V) (Digital Meter Reading)