DTC 2-2-3

2-2-3 IDLE AIR CONTROL VALVE SIGNAL

Condition(s) for DTC
^ The MFI module supplies pulsed ground signals to both coils of the Idle Air Control (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.