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.This DTC is a type A DTC.
Conditions for Setting the DTC
Power Up Test
| • | The engine is off |
| • | The ignition is ON for 2 seconds |
| • | The MAF sensor is no more than 2 g/s or greater than 300 g/s |
Low Frequency Test
| • | The engine is running. |
| • | Engine run time is greater than 2 seconds. |
| • | System voltage is at least 10.0 volts. |
| • | Throttle Position is less than 89.8%. |
| • | MAF signal frequency is no more than 2 g/s. |
| • | Above conditions present for over 2 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 or DTC
| • | The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed. |
| • | A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle. |
| • | Use a scan tool in order to clear the DTCs. |
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.
-
This step verifies that the problem is present at idle.
-
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
-
This step verifies that the ignition feed voltage and a good ground are available at the MAF sensor.
-
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 .
Step | Action | Value(s) | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 |
Important: Before clearing the DTCs, use the scan tool to record the Freeze Frame and the Failure Records for reference. This data will be lost when the Clear Info function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||||||
Is the MAF Frequency below the specified value? | 2 g/s | |||||||||||||
3 |
Does the scan tool indicate DTC P0102 failed this ign? | -- | Refer to Diagnostic Aids | |||||||||||
4 |
Was a problem found? | -- | ||||||||||||
Is the voltage near the specified value? | 5.0 V | |||||||||||||
Connect a test lamp between the MAF sensor ignition feed and ground circuits at the MAF sensor harness connector. Is the test lamp on? | -- | |||||||||||||
7 | Connect a test lamp between the MAF sensor ignition feed circuit and the battery ground. Is the test lamp on? | -- | ||||||||||||
8 |
If a poor connection is found, replace faulty terminals. Refer to Wiring Repairs in Engine Electrical. Was a poor connection found? | -- | ||||||||||||
9 |
Was the MAF signal circuit open or shorted? | -- | ||||||||||||
10 |
Is the action complete? | -- | -- | |||||||||||
11 |
Is the action complete? | -- | -- | |||||||||||
12 | Replace the MAF sensor. Refer to MAF Sensor Replacement . Is the action complete? | -- | -- | |||||||||||
Replace the VCM. Important: If the VCM is faulty, reprogram the VCM. Refer to VCM Replacement/Programming . Is the action complete? | -- | -- | ||||||||||||
14 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||||||||||||
15 | Using the scan tool, select the Capture Info and the Review Info. Are any DTCs displayed that have not been diagnosed? | -- | Go to Applicable DTC Tables | System OK |
