Honda Civic Service Manual page 470

ldle Gontrol System
The (Rotary) IAC Valve changes the amount of air bypassing the throttle body in response to a current signal from the
ECM/PCM in order to maintain the proper idle speed.
BIMETAL
HOLDER
BIMETAL
SHAFT VALVE
STOPPER
ECM/PCM CONNECTOR B {25P}
(To page 11-201)
IAC VALVE 3P CONNECTOR
IACV N
IACV P
ldle Air Control {lACl Valve ('99 - 00 A/T and Dl6Y7 enginel
YES
1P1509 lThescantool indicates Diagnostic Trouble Code (DTC) P1509:A problem inthe idleAirControl (lAC)valve circuit.
IGP
T e r m i n a l s i d e o f m a l e
t e r m i n a l s
Sub3titute e known-good ECM/
PCM .nd recheck. lf 3vmptom/
indicalion goos away, replac6
thc original ECM/PCM.
* : I A C V N l i n e
11-200
Tho MIL has b€en reported on.
OTC P1509 is sto.ed.
Problem verilicationr
1. Do the ECM/PCM Reset Proce-
dure.
2. Turn the ignition switch ON (ll).
Intermittont tailure, sy3tem i3 OK
at thb time. Check for poor con'
noctions or loose wiros at C109
(lAC velvel and ECM/PCM.
ls DTC P1509 indicated?
Check for an oDen in the wilos
IPG linesl:
Measure voltage between body
ground and ECM/PCM connector
terminals 82 and 810 individually.
Ropail open in the wires be'tw€en
ECM/PCM .nd G101 llocated .t
the the.mostat housingl.
ls there more than 1.0 V?
Check tho ECM/PCM input volt-
age:
1. Turn the ignition switch OFF.
2. Disconnect ECM/PCM connec-
tor A (32P)trom the ECM/PCM.
3. Turn the ignition switch ON (ll).
4 , M e a s u r e v o l t a g e b e t w e e n
body ground and ECM/PCM
c o n n e c t o r t e r m i n a l s 8 6 a n d
815* individually.
Chock the IAC v.lve:
1. Turn the ignition sw;tch OFF.
2. Disconnect the IAC valve 3P
connoctor.
3. Measure resistance between
IAC valve 3P connector termi'
nal No. 2 and terminals No. 1
and 3 individually.
ls there 16 - 28 O?
Wire side of female terminals