• | 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. |
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
---|---|---|---|---|---|
Ignition 1 Voltage | P0102 | P0101, P0102 | P0102 | -- | P0101, P0103 |
MAF Sensor Signal | P0102 | P0102 | P0102 | P0102 | P0101, P0103, P1101 |
Ground | -- | P0102 | P0102 | -- | P0102 |
Circuit | Normal Range | Short to Ground | Open | Short to Voltage |
---|---|---|---|---|
Ignition 1 Voltage | -- | 0 Hz | 0 Hz | -- |
MAF Sensor Signal | 1,700-9,500 Hz | 0 Hz | 0 Hz | 0 Hz |
Ground | -- | -- | 0 Hz | -- |
The mass air flow (MAF) sensor is integrated with the intake air temperature (IAT) sensor. The MAF sensor is an air flow meter that measures the amount of air entering the engine. The engine control module (ECM) 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/IAT sensor has the following circuits:
• | An ignition 1 voltage circuit |
• | A ground circuit |
• | A MAF sensor signal circuit |
• | An IAT sensor signal circuit |
• | A low reference circuit |
The ECM applies 5 volts to the MAF sensor on the MAF sensor 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 1,700 Hertz at idle to near 9,500 Hertz at maximum engine load.
• | The engine is running for more than one second. |
• | The engine speed is more than 300 RPM. |
• | The ignition 1 signal is more than 8 volts. |
• | The above conditions are met for more than one second. |
• | These DTCs run continuously within the enabling conditions. |
The ECM detects that the MAF Sensor parameter is less than 1,867 Hz for more than 5 seconds.
The ECM detects that the MAF Sensor parameter is more than 14,500 Hz for more than 5 seconds.
DTCs P0102 and P0103 are Type B DTCs.
DTCs P0102 and P0103 are Type B DTCs.
• | Verify the integrity of the air induction system by inspecting for the following conditions: |
- | A restricted or collapsed air intake duct |
- | A misaligned air intake duct |
- | A dirty or deteriorating air filter element |
- | Any objects blocking the air inlet screen of the MAF/IAT sensor |
- | Any water intrusion in the induction system |
- | Any contamination or debris on the sensing elements of the MAF sensor |
- | Damaged components |
- | Loose or improper installation |
- | Any air flow restriction |
- | Any vacuum leak |
• | 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 2-6 g/s at idle to 100 g/s or more at the time of the 1-2 shift. |
• | Verify that any electrical aftermarket devices are properly connected and grounded. Refer to Checking Aftermarket Accessories . |
• | Circuit Testing |
• | Wiring Repairs |
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
J 38522 Variable Signal Generator
Important: All electrical components and accessories must be turned OFF and allowed to power down.
⇒ | 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. |
To determine if the ECM can properly process the MAF sensor frequency signal, connect the J 38522 to the vehicle as follows:
⇒ | 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. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for ECM replacement, setup, and programming |