DTC 34

CIRCUIT DESCRIPTION
The Mass Air Flow (MAF) Sensor measures the flow of air entering the engine. The sensor produces a frequency output between 32 and 150 hertz. A large quantity (high frequency) indicates acceleration, and a small quantity (low frequency) indicates deceleration or idle. This information is used by the Engine Control Module (ECM) for fuel control.

Code 34 will set if:
^ Engine running
^ MAF sensor disconnected, faulty relay or MAF signal circuit shorted to ground.
OR
^ Air Flow less than 10 grams per second (low frequency).



CHART TEST DESCRIPTION
1. A loose or damaged air duct can set code 34.

2. Checks to see if ECM recognizes a problem. A light off at this point indicates an intermittent problem.

3. Checks to see if 5 volt reference signal from ECM is at MAF sensor harness connector. Less than I volt indicates a faulty CKT 492, wiring connector, or ECM.

4. Checks continuity of electrical circuit at MAF sensor.

5. Checks for open in 12 volt supply