Honda ACCORD HYBRID 2005 Service Manual page 278

Fuel and Emissions Systems
S y s t e m D e s c r i p t i o n ( c o n t ' d )
Idle Control System
W h e n the engine is cold, the A/C compressor is on, the
transmission is in gear, the brake pedal is pressed, the
power steering load is high, or the DC-DC converter is
charging, the PCM controls current to the throttle
actuator to maintain the correct idle speed.
Brake Pedal Position Switch
The brake pedal position switch signals the PCM w h e n
the brake pedal is pressed.
Electrical Power Steering (EPS) Signal
The EPS signals the PCM w h e n the p o w e r steering load
is high.
Idle Stop S w i t c h
The idle stop switch signals the PCM w h e n the brake
pedal is pressed.
Fuel Supply System
Fuel Cutoff Control
During deceleration w i t h the accelerator pedal closed,
current to the injectors is cut off to i m p r o v e fuel
e c o n o m y at engine speeds over 530 r p m (with auto idle
stop and brake pedal pressed), 750 r p m (with auto idle
stop and brake pedal released), 1,124 r p m (without auto
idle stop). Fuel cutoff control also occurs w h e n the
engine speed exceeds 6,600 r p m , regardless of the
position of the throttle valve, to protect the engine f r o m
o v e r - r e v v i n g . W h e n the vehicle is stopped, the PCM
cuts the fuel at engine speeds over 5,000 r p m . Engine
speed of fuel cut is lower on a cold engine.
Fuel Pump Control
W h e n the ignition is turned o n , the PCM grounds
PGM-FI main relay 2 (FUEL PUMP) w h i c h feeds current
to the fuel p u m p (fuel p u m p control module) for
2 seconds to pressurize the fuel system. W i t h the
engine running, the PCM grounds PGM-FI main relay 2
(FUEL PUMP) and feeds current to the fuel p u m p . W h e n
the engine is not running and the ignition is on, the
PCM cuts g r o u n d to PGM-FI main relay 2 (FUEL PUMP)
w h i c h cuts current to the fuel p u m p (fuel p u m p control
module).
PGM-FI Main Relay 1 and 2
PGM-FI main relay 1 (Fl MAIN) is energized whenever
the ignition switch is ON (II) to supply battery voltage to
the PCM, power to the injectors, and p o w e r for PGM-FI
main relay 2 (FUEL PUMP). PGM-FI main relay 2 (FUEL
PUMP) is energized to supply power to the fuel p u m p
for 2 seconds w h e n the ignition switch is turned ON (II),
and w h e n the engine is cranking or running.
Catalytic Converter System
Warm Up/Three Way Catalytic Converter (WU-TWC)
and Three Way Catalytic Converter ( T W O
The WU-TWC/TWC converts hydrocarbons (HC), carbon
m o n o x i d e (CO), and oxides of nitrogen (NOx) in the
exhaust gas to carbon dioxide (C0
2
), nitrogen (N
2
), and
water vapor.
WU-TWC: (ATTACHED TO THE CYLINDER HEAD)
FRONT REAR
FRONT OF
V E H I C L E
TWC: (UNDER THE FLOOR)
HOUSING
FRONT OF
V E H I C L E
T H R E E W A Y
C A T A L Y S T
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