Honda 2004 Odyssey Service Manual page 357

Fuel and Emissions Systems
System Descriptions (cont'd)
Power Steering Pressure (PSP) Switch
The PSP switch signals the PCM when the power
steering load is high.
Starter (Ignition) Switch
The starter switch signals the PCM when the engine is
cranking.
Fuel Supply System
Fuel Cut-off Control
During deceleration with the throttle valve closed,
current to the injectors is cut off to improve fuel
economy at engine speeds over 1,100 rpm.
Fuel cut-off action also occurs when engine speed
exceeds 6,600 rpm, regardless of the position of the
throttle valve, to protect the engine from over-revving.
When the vehicle is stopped, the PCM cuts the fuel at
engine speeds over 5,000 rpm.
Fuel Pump Control
When the ignition is turned on, the PCM grounds the
PGM-FI main relay which feeds current to the fuel pump
for 2 seconds to pressurize the fuel system. With the
engine running, the PCM grounds the PGM-FI main
relay and feeds current to the fuel pump. When the
engine is not running and the ignition is on, the PCM
cuts ground to the PGM-FI main relay which cuts
current to the fuel pump.
Fuel Gauge Sending Unit
The fuel gauge sending unit measures the fuel level in
the fuel tank. The fuel gauge sending unit output
changes according to the float position.
To GAUGE
ASSEMBLY
FUEL TANK
11-48
'03-04 models
YEL/BLU
BLK
FUEL GAUGE SENDING UNIT
PGM-FI Main Relay
The PGM-FI relay contains 2 separate relays. One is
energized whenever the ignition is on which supplies
battery voltage to the PCM, power to the fuel injectors,
and power for the second relay. The second relay is
energized to supply power to the fuel pump for
2 seconds when the ignition is switched ON (II), during
engine cranking, and when the engine is running.
Intake Air System
Refer to the System Diagram to see a functional layout
of the system.
Heated Air Induction System
The heated air induction system improves fuel
economy in cold weather conditions and when the
engine is cold.
When outside air temperature is low, the air
temperature control valve opens the air valve to allow
heated air into the engine.
AIR VALVE
AIR TEMPERATURE
CONTROL VALVE