DTC 3-2-2

3-2-2 MASS AIR FLOW SENSOR BURNOFF




Trouble Code Conditions
If voltage across Engine Control Module (ECM) # 7 during burnoff is less than 2.5 volts, Diagnostic Trouble Code (DTC) 3-2-2 is set.

Substitute value(s)
- None.

Fault source(s)
- Break in signal lead.
- Signal lead short circuited to ground.
- Contact resistance in connectors.

Fault symptom(s)
- None.

TEST PROCEDURE




OTHER DTC'S
- Read off other DTCs.

If DTC 1-2-1 is stored:
^ Fault trace DTC 1-2-1, MAF sensor signal.

If DTC 1-2-1 is not stored:
^ Status report. Proceed to STATUS REPORT section below.




STATUS REPORT
- Start engine and allow to idle until engine temperature exceeds 60°C (140°F).
- Increase engine revs to over 1800 rpm.
- Ignition off, wait approx. 30 seconds.
- Ignition on.
- Read off DTC.

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

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

PERMANENT FAULT, SIGNAL TOO LOW
Check signal lead resistance
- Ignition off.
- Disconnect Mass Air Flow (MAF) sensor.



- Connect an ohmmeter between MAF sensor connector contact 4 and ground.

Ohmmeter should read very high or infinite resistance.

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

If value is approx. 0 ohms:
^ Check lead between ECM # 25 and MAF sensor connector 4 for short circuit to ground.

CHECK SIGNAL LEAD
- Ignition off.
- MAF sensor disconnected.
- Ignition on.



- Connect a voltmeter between MAF sensor connector contact 4 and battery positive pole.

Voltmeter should read battery voltage.

If value OK:
^ Source of DTC is bad contact in ECM and/or MAF sensor connector. Check connector for contact resistance and oxidation.

If value differs:
^ Check ECM connector. Proceed to CHECK ECM CONNECTOR section below.




CHECK ECM CONNECTOR
- Ignition off.
- MAF sensor disconnected.
- Check ECM connector for contact resistance and oxidation.
- ECM connected.
- Ignition on.



- Connect a voltmeter between MAF sensor connector and battery positive pole.

Voltmeter should read battery voltage.

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

If value differs:
^ Check lead between ECM # 25 and MAF sensor connector 4 for break.




INTERMITTENT FAULT, SIGNAL TOO LOW
- Check lead between ECM # 25 and MAF sensor connector 4 for intermittent break, as well as for intermittent short circuit to ground.
- Check MAF sensor and ECM connector for bad contact, as well as contact resistance and oxidation.