P0103

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 Vehicle Control Module (VCM) uses the Mass Air Flow information for the fuel delivery calculations. A large quantity of air entering the engine indicates an acceleration or a high load situation, while a small quantity of air indicates a deceleration or a idle situation.

The MAF sensor produces a frequency signal which a scan tool can monitor. 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

High Frequency Test

^ The engine is running.

^ Engine Run Time is at least 0.4 seconds.

^ System voltage is at least 8 volts.

^ Above conditions present for 0 seconds.

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 start-up 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:

^ Poor connection at 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 the 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 connectors and wiring harnesses related to the MAF sensor. A change in the display will indicate the location of the fault.

TEST DESCRIPTION

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

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

4. A frequency reading with the MAF sensor connector disconnected indicates an Electromagnetic Interference (EMI) related fault or a poor connection.