P0102

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

The Mass Air Flow (MAF) sensor measures the amount of air entering the engine during a given time. The VCM uses the Mass Air Flow information for fuel delivery calculations. A large quantity of air entering the engine indicates an acceleration or high load situation, while a small quantity of air indicates deceleration or idle.

The MAF sensor produces a frequency signal which can be monitored with a scan tool. The frequency varies within a range of around 5 to 7 g/s at idle to near 125 g/s at maximum engine load.

CONDITIONS FOR SETTING THE DTC

Power Up Test

^ The engine is OFF.

^ The ignition is ON for 2 seconds.

^ MAF sensor is no more than 60Hz.

Low Frequency Test

^ The engine speed is greater than or equal to 300 RPM.

^ Engine run time is greater than 0.2 seconds.

^ System voltage is greater than 10 volts.

^ Throttle Position is less than 89.8%.

^ MAF signal frequency is no more than 300Hz.

^ Above conditions present for greater than 2 seconds.

^ This DTC sets if the signal from the MAF senor measures below the possible range of a normally operating MAF sensor.

ACTION TAKEN WHEN THE DTC SETS

^ The VCM illuminates the Malfunction Indicator Lamp (MIL) the first time the fault is detected.

^ The VCM calculates an airflow value based on the Idle Air Control (IAC) valve position, throttle position, engine speed and barometric pressure.

^ The VCM stores the conditions which were present when the DTC set as Freeze Frame and the Fail Records data.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The VCM turns the MIL OFF after 3 consecutive drive trips when the test has Run and Passed and not Failed.

^ A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant temperature exceeds 70°C (160°F) during the same ignition cycle).

^ Use the scan tool Clear Information function.

^ Disconnect the VCM battery feed for 30 seconds.

DIAGNOSTIC AIDS

Check for the following conditions:

^ A poor connection at the VCM. Inspect harness connectors for the following conditions:

- Backed out terminals

- Improper mating

- Broken locks

- Improperly formed or damaged terminals

- Poor terminal to wire connection

^ A misrouted harness. Inspect the MAF sensor harness in order to ensure that it is not routed too close to high voltage wires such as spark plug leads.

^ A damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving the connectors and the wiring harnesses related to the MAF sensor. A change in the display indicates the location of the fault.

^ A plugged intake air duct or filter element. A wide open throttle acceleration from a stop should cause the Mass Air Flow displayed on a scan tool to increase from about 4-7 g/s at idle to 100 g/s or greater at the time of the 1-2 shift. If not, check for a restriction.

TEST DESCRIPTION

The numbers below refer to step numbers on the diagnostic table.

2. This step verifies that the problem is present at idle.

6. A voltage reading of less than 4 or over 6 volts at the MAF sensor signal circuit indicates a fault in the wiring or a poor connection

7. This step verifies that the ignition feed voltage and a good ground are available at the MAF sensor.

11. This step determines if the fuse is open. If the fuse is open, locate and repair the short to ground in the Ignition Positive Voltage circuit. Refer to Fuse Block.

15. This vehicle is equipped with a VCM. The VCM utilizes an Electricity Erasable Programmable Read Only Memory (EEPROM). When the VCM is being replaced, reprogram the VCM. Refer to VCM Replacement/Programming.