DTC 2-2-3

2-2-3 IDLE AIR CONTROL (IAC) VALVE SIGNAL

Condition(s) for DTC
^ The MFI module supplies pulsed ground signals to both coils of the IAC valve, one to the opening coil and the other to the closing coil, to maintain a constant idling speed. The DTC is recorded if the module senses a fault in the IAC valve or its wiring.

Substitute value
^ None. The control module will attempt to close the valve if the speed exceeds 1400 rpm.

Fault source(s)
^ Signal lead open-circuit.
^ Signal lead short-circuited to ground or supply.
^ Open-circuit in valve supply lead.
^ Contact resistance in connections.
^ Faulty IAC valve.

Fault symptom(s)
^ Engine is difficult to start or fails to start.
^ Low or high idling speed.

TESTING PROCEDURE





Other DTCs
^ Read other DTCs.

If MFI DTC 4-1-1 is recorded:
- Proceed to DTC 4-1-1 Throttle Position (TP) Potentiometer.
If MFI DTC 4-1-1 is not recorded:
- Check Status message.





Status message
^ Check the current Statue message.

If Status message is: Permanent fault, signal faulty:
- Proceed to PERMANENT FAULT, SIGNAL FAULTY Section below.
If Status message is: Intermittent fault, signal faulty:
- Proceed to INTERMITTENT FAULT, SIGNAL FAULTY Section below.

PERMANENT FAULT, SIGNAL FAULTY





Checking supply lead
^ Switch ON ignition.
^ Disconnect IAC valve.
^ Connect voltmeter between IAC valve connector terminal 2 and ground.

Instrument should indicate battery voltage.

If reading is correct:
- Check signal lead (opening coil).
If reading is incorrect:
- Check lead between main relay (2/32) terminal 3 and IAC valve connector terminal 2 for open-circuit.





Checking signal lead (opening coil)
^ Switch ON ignition.
^ Disconnect IAC valve.
^ Connect voltmeter between IAC valve connector terminal 3 and ground.

Instrument should indicate less than 1 Volt.

If reading is correct:
- Check resistance of signal lead (opening coil) to ground.
If reading is incorrect:
- Check lead between MFI module A16 and IAC valve connector terminal 3 for short-circuit to supply.





Checking resistance of signal lead (opening coil) to ground
^ Switch OFF ignition.
^ Disconnect IAC valve.
^ Connect ohmmeter between IAC valve connector terminal 3 and ground.

Instrument should indicate 20 - 60K Ohms.

If reading is correct:
- Check signal lead (closing coil).
If resistance is infinite (no continuity):
- Check lead between MFI module A16 and IAC valve connector terminal 3 for open-circuit.
If resistance is approx. 0 Ohms:
- Check lead between MFI module A16 and IAC valve connector terminal 3 for short-circuit to ground.





Checking signal lead (closing coil)
^ Switch ON ignition.
^ Disconnect IAC valve.
^ Connect voltmeter between IAC valve connector terminal 1 and ground.

Instrument should indicate less than 1 Volt.

If reading is correct:
- Check resistance of signal lead (closing coil) to ground.
If reading is incorrect:
- Check lead between MFI module A17 and IAC valve connector terminal 1 for short-circuit to supply.





Checking resistance of signal lead (closing coil) to ground
^ Switch OFF ignition.
^ Disconnect IAC valve.
^ Connect ohmmeter between IAC valve connector terminal 1 and ground.

Instrument should indicate 150 - 250K Ohms.

If reading is correct:
- Check signal lead (closing coil).
If resistance is infinite (no conductivity):
- Check lead between MFI module A17 and IAC valve connector terminal 1 for open-circuit.
If resistance is approx. 0 Ohms:
- Check lead between MFI module A17 and IAC valve connector terminal 1 for short-circuit to ground.





Checking IAC valve
^ Switch OFF ignition.
^ Disconnect IAC valve.
^ Connect ohmmeter between IAC valve connector terminals 1 and 2.
^ Read value.
^ Connect ohmmeter between IAC valve connector terminals 2 and 3.
^ Read value.

Instrument should indicate 9 - 15 Ohms in both cases.

If reading is correct:
- DTC is due to poor connection in IAC valve connector. Check connector for contact resistance and oxidation.
If reading is incorrect:
- Try with new IAC valve.

INTERMITTENT FAULT, SIGNAL FAULTY





Checking wiring and connectors
^ Check IAC valve and MFI module connectors for contact resistance and oxidation.
^ Check lead between MFI A17 and IAC valve connector terminal 1 and between MFI A16 and IAC valve connector terminal 3, for intermittent open-circuit, intermittent short-circuit to ground or intermittent short-circuit to supply.
^ Check lead between main relay (2/32) terminal 3 and IAC valve connector terminal 2 for intermittent open-circuit.