Honda Civic Service Manual page 468

ldle Control System
ldle Air Control (lAC) Valve ('96 - 98 A/T and Dl6Y7 enginel
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
VALVE
STOPPER
1P1509 Thescantool indicates Diagnostic Trouble Code (DTC) P1509: A problem in the idle Air Control (tAC)valve circuit.
ECM/PCM CONNECTOR A I32PI
PGl IBLKI
IAC VALVE 3P CONNECIOR
IACV N
IACV P
IGP
Terminal side of male
terminals
* : I A C V N l i n e
1 1 - 1 9 8
The MIL has b€€n roported on.
DTC P1509 is stored.
Problem verification:
1. Do the ECM/PCM Reset Proce-
oure.
2. Turn the ignition switch ON (ll).
Intermittent failura, systom ia OK
at this time. Check tor poo. con-
noctions or loose wires at C109
llAC valve) and ECM/PCM.
ls DTC P1509 indicated?
Check for an opon in the wirer
{PG lines):
Measure voltage between bodv
ground and ECM/PCII connector
terminals A10 and A23 individu
Repair op€n in the wires betwoen
ECM/PCM and G101 llocated at
tho thermostat housing).
ls there more than 1.0 V?
Chock th€ ECM/PCM inpui volt-
agel
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
b o d y g r o u n d a n d E C M / P C M
connector terminals A14 and
A13* individually.
Ch6ck th6 IAC valve:
1. Turn the ignition switch OFF.
2. Disconnect the IAC valve 3P
connector,
3, Measure resistance between
IAC valve 3P connector termi-
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 g?
Substitute a known-good ECM/
P C M a n d r e c h e c k . l f s y m p t o m /
i n d i c a t i o n g o o s a w a y , r e p l a c e
th€ origin.l ECM/PCM.
SHAFT
rAcv N loRNl*
( T o p a g e 1 1 - 1 9 9 )
Wire side of lemale terminals
1
2
3
a
5 6
E
l 0 1 1
12
1 3 1 4
r 5
1 6 1 7 1 8 t9 20 2:2 23 21
27
2A
A
30
IACV P {BLK/BLUI