Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC P0102: Mass Air Flow (MAF) Sensor Circuit Low FrequencyDTC P0103: Mass Air Flow (MAF) Sensor Circuit High Frequency
Diagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
Ignition 1 Voltage | P0102 | P0101 | P0102 | -- | P0101, P0103 |
MAF Sensor Signal | P0102 | P0102 | P0102 | P0102 | P0101, P0103 |
Ground | -- | P0102 | P0102 | -- | P0102 |
Circuit/System Description
The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The control module uses the MAF sensor signal to provide the correct fuel delivery for all engine speeds and loads. A small quantity of air entering the engine indicates a deceleration or idle condition. A large quantity of air entering the engine indicates an acceleration or high load condition. The MAF sensor has the following circuits:
| • | An ignition 1 voltage circuit |
| • | A ground circuit |
| • | A signal circuit |
The control module applies a voltage to the sensor on the signal circuit. The sensor uses the voltage to produce a frequency based on the inlet air flow through the sensor bore. The frequency varies within a range of near 2,000 Hertz at idle to near 10,000 Hertz at maximum engine load.
Conditions for Running the DTC
| • | The engine is cranking or running. |
| • | The engine speed is more than 50 RPM. |
| • | The ignition 1 signal is more than 8 volts. |
| • | The TP indicated angle parameter is more than 3.5 percent. |
| • | The above conditions are met for more than 0.5 second. |
Conditions for Setting the DTC
P0102
The control module detects that the MAF sensor frequency signal is less than 1,200 Hertz for more than 10 seconds.
P0103
The control module detects that the MAF sensor frequency signal is more than 11,500 Hertz for more than 10 seconds.
Action Taken When the DTC Sets
DTCs P0102 and P0103 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0102 and P0103 are Type B DTCs.
Diagnostic Aids
| • | Inspect the harness of the MAF sensor to verify that it is not routed too close to the following components: |
| - | The secondary ignition wires or coils |
| - | Any solenoids |
| - | Any relays |
| - | Any motors |
| • | A wide open throttle (WOT) acceleration from a stop should cause the MAF sensor parameter on the scan tool to increase rapidly. This increase should be from 3-10 g/s at idle to 150 g/s or more at the time of the 1-2 shift. If the increase is not observed, inspect for a restriction in the induction system or the exhaust system. |
| • | A high resistance may cause a driveability concern before this DTC sets. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Special Tools Required
J 38522 Variable Signal Generator
Circuit/System Testing
Important: All electrical components and accessories must be turned OFF and allowed to power down.
- Ignition OFF, disconnect the MAF/IAT harness connector at the MAF/IAT sensor.
- Ignition OFF, test for less than 5 ohms of resistance between the ground circuit terminal C and ground.
- Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal B and ground.
- Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal A and ground.
- Connect the J 38522 to the vehicle. Refer to Component Testing for instructions.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. |
| ⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM. |
Component Testing
To determine if the ECM can properly process the MAF sensor frequency signal, connect the to the vehicle as follows:
- Turn OFF the ignition.
- Connect the battery voltage supply and ground the black lead.
- Connect the red lead to the signal circuit of the MAF sensor.
- Set the duty cycle switch to Normal.
- Set the Frequency switch to 5 K.
- Set the Signal switch to 5 volts.
- Start the engine.
- Observe the MAF Sensor parameter for the correct range of 4,950-5,025 Hz.
| ⇒ | If the MAF Sensor parameter is not within the specified range, replace the ECM. |
| ⇒ | If the MAF Sensor parameter is within the specified range, replace the MAF sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
