DTC 2-2-3

2-2-3 IDLE AIR CONTROL VALVE SIGNAL




Trouble Code Conditions
The Engine Control Module (ECM) sends pulsed ground signals to the Idle Air Control (IAC) valve to maintain an even idle. The ECM can compare battery voltage with voltage across the IAC valve to determine if there is a fault in the leads or in the IAC valve itself.

Substitute value(s)
- None.

Fault source(s)
Signal too high # 4:
- Signal lead short circuit to live.
- Signal lead broken.
- Contact resistance in connections.
- Defective IAC valve.

Signal too low # 4:
- Signal lead short circuit to ground.

Signal too high # 22:
- Signal short circuit to live.
- Defective IAC valve.

Signal too low # 22:
- Signal lead short circuit to ground.
- Power lead broken.
- Signal lead broken.
- Contact resistance in connections.
- Defective IAC valve.

Signal absent # 22:
- Signal lead intermittent short circuit to ground.
- Signal lead intermittent short circuit to live.
- Bad contact and contact resistance in connections.

Fault symptom(s)
- Low or high idle speed.
- Engine difficult to start.

TEST PROCEDURE




STATUS REPORT
^ Permanent fault, signal too high # 4:
- Proceed to: PERMANENT FAULT, SIGNAL TOO HIGH # 4 section below.

^ Permanent fault, signal too low # 4:
- Proceed to: PERMANENT FAULT, SIGNAL TOO LOW # 4 section below.

^ Intermittent fault, signal too high # 4:
- Proceed to: INTERMITTENT FAULT, SIGNAL TOO HIGH # 4 section below.

^ Intermittent fault, signal too low # 4:
- Proceed to: INTERMITTENT FAULT, SIGNAL TOO LOW # 4 section below.

^ Signal too high # 22:
- Proceed to: SIGNAL TOO HIGH # 22 section below.

^ Signal too low # 22:
- Proceed to: SIGNAL TOO LOW # 22 section below.

^ Signal absent # 22:
- Proceed to: SIGNAL ABSENT # 22 section below.




PERMANENT FAULT, SIGNAL TOO HIGH # 4
Check signal lead
- Ignition off.
- Disconnect IAC valve.
- Ignition on.
- Connect a voltmeter between IAC valve connector contact 3 and ground.

Voltmeter should read 6.0 - 9.5 volts.

If values OK:
^ Check IAC valve. Proceed to CHECK IAC VALVE section below.

If voltmeter reads battery voltage:
^ Check lead between IAC valve connector contact 3 and ECM # 4 for short circuit to live.

If voltmeter reads approx. 0 volts:
^ Check connector. Proceed to CHECK CONNECTOR section below.




CHECK CONNECTOR
- Ignition off.
- Disconnect IAC valve.
- Check ECM connector and 55-pin connector in central relay unit (A3/E) connector contact 1 for contact resistance and oxidation.
- ECM connected.
- Ignition on.



- Connect a voltmeter between IAC valve connector contact 3 and ground.

Voltmeter should read 6.0 - 9.5 volts.

If values OK:
^ Source of fault is bad contact in connectors.

If values differ:
^ Check lead between IAC valve connector contact 3 and ECM # 4 for break.




CHECK IAC VALVE
- Ignition off.
- IAC valve disconnected.
- Connect an ohmmeter between IAC valve pins 3 and 2.

Ohmmeter should read 10 - 14 ohms.

If values OK:
^ Source of DTC is bad contact in IAC valve connector.
^ Check connector for contact resistance and oxidation.

If values differ:
^ Test with a new IAC valve.




PERMANENT FAULT, SIGNAL TOO LOW # 4
Check leads
- Ignition off.
- Check lead between IAC valve connector contact 3 and ECM # 4 for short circuit to ground.

INTERMITTENT FAULT, SIGNAL TOO HIGH # 4
Check leads and connections
- Check lead between IAC valve connector contact 3 and ECM # 4 for intermittent break, and intermittent short circuit to live.
- Check 55-pin connector in central relay unit (A3/E) connector contact 1, IAC valve and ECM connector for bad contact and contact resistance and oxidation.

INTERMITTENT FAULT, SIGNAL TOO LOW # 4
Check leads and connections
- Check lead between IAC valve connector contact 3 and ECM # 4 for intermittent short circuit to ground.




SIGNAL TOO HIGH # 22
Check signal lead
- Ignition off.
- Disconnect IAC valve.
- Ignition on.
- Connect a voltmeter between ground and IAC valve connector contact 1.

Voltmeter should read 6.0 - 8.5 volts.

If values OK:
^ Test with a new IAC valve.

If values differ:
^ Check lead between IAC valve connector contact and ECM # 22 for short circuit to live.




SIGNAL TOO LOW # 22
Check power lead
- Ignition off.
- Disconnect IAC valve.
- Ignition on.
- Connect a voltmeter between IAC valve connector contact 2 and ground.

Voltmeter should read battery voltage.

If values OK:
^ Check signal lead. Proceed to CHECK SIGNAL LEAD section below.

If values differ:
^ Check lead between IAC valve connector contact 2 and injection valves connector contact 1 for break.




CHECK SIGNAL LEAD
- Ignition off.
- IAC valve disconnected.
- Connect an ohmmeter between IAC valve connector contact 1 and ground.

Ohmmeter should read 1 - 4 k ohms.

If values OK:
^ Check IAC valve. Proceed to CHECK IAC VALVE section below.

If ohmmeter reads approx. 0 ohms:
^ Check lead between IAC valve connector contact and ECM # 22 for short circuit to ground.

If ohmmeter reads infinite resistance:
^ Check connector. Proceed to CHECK CONNECTOR section below.




CHECK CONNECTOR
- Ignition off.
- IAC valve disconnected.
- Check ECM connector and 55-pin connector in central relay unit (A3/E) connector contact 2 for contact resistance and oxidation.
- ECM connected.



- Connect an ohmmeter between IAC valve connector contact 1 and ground.

Ohmmeter should read 1 - 4 k ohms.

If values OK:
^ Source of DTC is bad contact in connector.

If values differ:
^ Check lead between IAC valve connector contact 1 and ECM # 22 for break.




CHECK IAC VALVE
- Ignition off.
- IAC valve disconnected.
- Connect an ohmmeter between valve pins 3 and 2.

Ohmmeter should read 10 - 14 ohms.

If values OK:
^ Source of DTC is bad contact in IAC valve connector.
^ Check connector for contact resistance and oxidation.

If values differ:
^ Test with a new IAC valve.




SIGNAL ABSENT # 22
Check leads and connections
- Check lead between IAC valve connector contact 1 and ECM # 22 for intermittent short circuit to ground, and intermittent short circuit to live.
- Check IAC valve and ECM connector for bad contact and contact resistance and oxidation.