Without Speed Density Update

Chart - Code 34 Mass Air Flow Sensor (Signal Frequency Low):

Wiring Diagram for Mass Air Flow Sensor Circuit:

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 (3gm/sec to 150gm/sec.). A large quantity (high frequency) indicates acceleration, and a small quantity (low frequency) indicates deceleration or idle. This information is used by the Electronic Control Module (ECM) for fuel control and is converted by a "Scan" tool to read out the air flow in grams per second. A normal reading is about 4-7 grams per second at idle and increase with rpm.
The MAF Sensor is powered up by the MAF Sensor relay (mounted on the left shock tower) and the Sensor should have power supplied to it anytime the ignition is "ON."

TEST DESCRIPTION:
Numbers below refer to circled numbers on the diagnostic chart.
1. Code 34 will set if:
- Engine running
- MAF sensor disconnected, faulty relay, or MAF signal circuit shorted to ground.
- Air Flow less than 2 grams per second (low frequency). A loose or damaged air duct can set Code 34. This test checks to see if ECM recognizes a problem. A light "OFF" at this point indicates an intermittent problem.
2. Checks to see if 5 volt reference signal from ECM is at MAF sensor harness connector.
3. Checks continuity of electrical circuit at MAF sensor.
4. Checks for open in 12 volt supply.

DIAGNOSTIC AIDS:
The "Scan" tool is not of much use in diagnosing this code because when the code sets gm/sec will be displaying the default value. It may be useful in comparing the signal of a problem vehicle with that of a known good running one. Verify that the sensor is not contaminated. Check for loose or damaged air duct, or other problems, which may cause low air now, such as misadjusted minimum idle speed or vacuum leaks. Inspect sensor and relay connections, as an open will result in a Code 34. See "DIAGNOSIS BY SYMPTOMS." Testing and Inspection