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 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 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. This DTC sets if the signal from the MAF sensor is above the possible range of a normally operating MAF sensor. This DTC is a type A DTC.

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 8.0 volts.

^ MAF sensor is at least 10400 Hz.

^ The above must be present for a period of time greater than 0.0 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 Idle Air Control (IAC) valve position, throttle position, engine speed and barometric pressure.

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

Conditions for Clearing the MIL/DTC

^ The VCM turns the MIL off on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.

^ A history DTC clears after 40 consecutive warm-up cycles have occurred without a fault.

^ Using the scan tool Clear Info function or disconnecting the VCM battery feed clears the DTC.

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.

9. This vehicle is equipped with a VCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the VCM is being replaced, the new VCM must be programmed. Refer to VCM Replacement/Programming.