Daewoo MATIZ Service Manual page 344

1F – 246 ENGINE CONTROLS
IDLE AIR CONTROL VALVE (IACV) CIRCUIT FAULT
Circuit Description
The Engine Control Module (ECM) controls the air en-
tering into the engine with an Idle Air Control (IAC)
Valve. To increase the idle rpm, the ECM commands the
pintle inside the IAC valve away from the throttle body
seat. This allows more air to bypass through the throttle
blade. To decrease the rpm the ECM commands the
pintle towards the throttle body seat. This reduces the
amount of air bypassing the throttle blade. A scan tool
will read the IAC valve pintle position in counts. The
higher the counts, the more air that is allowed to bypass
the throttle blade. This Diagnostic Trouble Code (DTC)
determines if a low idle condition exists as defined as
100 rpm below the desired idle rpm.
Conditions for Setting the DTC
D No intrusive tests are active.
D DTC(s) P0106, P0107, P0108, P0112, P0113,
P0117, P0118, P0122, P0123, P0131, P0132,
P0133, P1133, P1134, P0171, P1171, P0172, P0201,
P0202, P0203, P0204, P0300, P0336, P0337,
P0341, P0342, P0351, P0352, P0402, P0404,
P1404, P0405, P0406, P0443, and P0502 are not
set.
D Engine is running more than 60 seconds.
D Barometric Pressure (BARO) is greater than 72 kPa
(10.4 psi).
D Engine Coolant Temperature (ECT) is greater than
60_C (140_F).
D Ignition voltage is between 11 and 16 volts.
D The Intake Air Temperature (IAT) is greater than
–20_C (–4_F).
D Manifold Absolute Pressure is less than 60 kPa (8.7
psi).
DIAGNOSTIC TROUBLE CODE (DTC) 0505
D IAC valve is controlled fully opened.
D All of the above must be met for greater than 5 sec-
onds.
Action Taken When the DTC Sets
D The Malfunction Indicator Lamp (MIL) will illuminate.
D The ECM will record operating conditions at the time
the diagnostic fails. This information will be stored in
the Freeze Frame and Failure Records buffers.
D A history DTC is stored.
Conditions for Clearing the MIL/DTC
D The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
D A history DTC will clear after 40 consecutive warm-up
cycles without a fault.
D DTC(s) can be cleared by using the scan tool.
D Disconnecting the ECM battery feed for more than 10
seconds.
Diagnostic Aids
Inspect the IAC valve electrical connection for proper
mating.
Inspect the wiring harness for damage.
Inspect the throttle stop screw for signs of tampering.
Inspect the throttle linkage for signs of binding or exces-
sive wear.
A slow or unstable idle may be caused by one of the fol-
lowing conditions:
D Fuel system too rich or too lean.
D Foreign material in the throttle body bore or in the air
induction system.
D A leaking or restricted intake manifold.
MAA1F070
DAEWOO M-150 BL2