Honda Civic 1998 Service Manual page 317

ldle Gontrol System
ldle Air Control (lACl Valve (A/T and Dl6Y7 engine)
lTi509l
Th""""ntool indicates Diagnostjc Trouble Code (DTC) P1509:Aproblem inthe idleAirControl (lAC) valve circuit.
The (Rotary) IAC Valve changes the amount ot air bypassing the throttle body in response lo a current signal trom the
ECM/PCM in order to maintain the proper idle speed.
BIMElAL
v
Problom verification:
1. Do the ECM/PCM Reset Proce-
dure,
2. Turn the ignition switch ON (ll).
SHAFT
VALVE STOP?ER
ECM/PCM CONNECTOR A I32P}
IAC VALVE 3P CONNECTOB
IACV N IACV P
PGl (BIK}
\3
tAcv N {oRNt.
(To page 11 129)
IGP
Terminal side of male
Iermtnals
* : I A C V N l i n e
11 -1 2 8
The MIL has been reooned on.
DTC Pl 5'lx) is sto.ed.
Intermittent failuro, svstem ia OK
at lhis time. Check for poor con-
nections or 10036 wires at C109
{lAC valve) end ECM/PCM.
ls DTC P1509 iodicated?
Check for an open in the wires
IPG lin6):
Measure voltage between body
ground and ECM/PCM connector
terminals A10 and A23 individu
Repair op6n in lhe wires between
E C M / P C M a n d G 1 0 1 { l o c a t 6 d a r
the thermostat housing.l
ls there more than 1.0 V?
Check the ECM/PCM inpul volt-
age:
1. Turn the ignition switch OFF.
2. Disconnect ECM/PCM connec-
tor A (32P) from 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
connector terminals A14 and
A13+ individually.
ls there baftery vohage?
Check the IAC valve:
1 . T u r n t h e i g n i t i o n s w i t c h O F F .
2 . D i s c o n n e c t t h e I A C v a l v e 3 P
c o n n e c t o r .
3 . M e a s u r e r e s i s t a n c e b e t w e e n
I A C v a l v e 3 P c o n n e c t o r t e r m i '
n a l N o . 2 a n d t e r m i n a l s N o . 1
a n d 3 i n d i v i d u a l l y .
ls there 16- 28 O?
Substiluto a known-good ECM/
PCM and rocheck. lf symptom/
indicalion goes away, replace
the original ECM/PCM.
Wire sid€ ol temale terminals
2
I 8
1 0
1'l
1 2 l 1 3
1 a 1 5 1 6 1 7 t8
t9
m
22 23
2a
. l
O)
27
28 29
3o
IACV P IBLK/BLU}