Idle Control System - Honda CR-V 1997 Service Manual

Idle Control System
System Description
The idle speed of the engine is controlled by the Idle Air ControlllACI Valve ,
Th e valve changes the amount of air bypassing into the intake manifold in response to electric current controlled by the
ECM/PCM. When the lAC Valve is activated, the va lve opens to maintain the proper idle speed.
INTAKE MAINIF')LD
, -__ Y::EL/ _ __ _ _ __ _ _ _ _ __ _ . .
OIII
From PGM·FI
MAIN RELAY
BLK/ _ _ _ __ _ _ _ __ _ _ _
----¢
BLU
IA/TI
r---··-'
I
ENGINE
' I '
COOLANT ,
I
t
'FAST
,IDLE
I
'THERMO
VALVE
ECMI
PCM
BLK
..1
VARIOUS
SENSORS
1. Aher the engine starts, the lAC valve opens for a certai n time . The amount of air is increased to raise the idle speed
about 150 - 300 rpm.
2. When the coolant temperature is low, the lAC valve is opened to obtain the proper fast idle speed. The amount of
bypassed air is thus controlled in relation to the engine coo lant temperature .
3. When the idle speed is out of specification and the scan tool does not indicate Diagnostic Trouble Code (OTC) P050S
or P1S08, check the following items;
Adjust the idle speed Isee page 11·169, 170)
Air conditioning signal (see page 11-155)
ALT FR signallsee page 11·159)
Starter switch signal (see page 11-161)
A!f
gear position signal (see section 14)
PSP switch signallsee page 11·162)
Brake switch signa l (see page 11-166)
Fast idle thermo valve (see page 11-168)
Hoses and connections
lAC va lve and its mounting O-rings
4, If the above items are normal, substitute a known -good lAC valve and readjust the idle speed (see page 11-169,170).
If the idle speed still cannot be adjusted to specification (and the scan tool does not indicate OTC P050S or P1508)
after lAC valve replacement, substitute a known-good ECM/PC M and recheck . If symptom goes away, replace the
original ECM/PCM .
11-149