Idle Control System; Fuel Supply System; Brake Pedal Position Switch; Electrical Power Steering (Eps) Senser - Honda Civic 2002-2003 Service Manual

Fuel and Emissions Systems
System Descriptions (cont'd)
Idle Control System
When the engine is cold, the AlC compressor is on, the
transmission is in gear, the brake pedal is pressed, the
power steering load is high, or the alternator is
charging, the ECM controls current to the Idle Air
Control (lAC) valve to maintain the correct idle speed.
Refer to the System Diagram to see the functional
layout of the system.
Brake Pedal Position Switch
The brake pedal position switch signals the ECM when
the brake pedal is pressed.
Electrical Power Steering (EPS) Senser
The EPS sensor signals the ECM when the power
steering load is high.
Idle Air Control (lAC) Valve
To maintain the proper idle speed, the lAC valve
changes the amount of air bypassing the throttle body
in response to an electrical signal from the ECM.
From AIR To INTAKE
CLEANER MANIFOLD
lAC VALVE
11-32
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 1,030 rpm. Fuel cut-off
action also occurs when engine speed exceeds
6,900 rpm, regardless of the position of the throttle
valve, to protect the engine from over-revving. When
the vehicle is stopped, the ECM cuts the fuel at engine
speeds over 6,500 rpm.
Fuel Pump Control
When the ignition is turned on, the ECM 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 ECM grounds the PGM·FI main
relay and feeds current to the fuel pump. When the
engine is not running and the jgnition is on, the ECM
cuts ground to the PGM·FI main relay which cuts
current to the fuel pump.
PGM·A Main Relay 1 and 2
The PGM·FI main relay consists of two separate relays.
Relay 1 is energized whenever the ignition switch is ON
(II) to supply battery voltage to the ECM power to the
injectors, and power for relay. Relay 2 is energized to
supply power to the fuel pump for 2 seconds when the
ignition switch is turned ON (II), and when the engine is
running.
•