• | 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 provide 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 |
MAF Sensor Signal | P0102 | P0101 | P0102 | P0101, P0102, P0401 | P0101 |
Low Reference | -- | -- | -- | -- | -- |
Circuit | Short to Ground | Open | Short to Voltage |
---|---|---|---|
Operating Conditions: Engine running at idle, ECT sensor greater than 60°C (140°F) Parameter Normal Range: 2,300-3,100 Hz and 10-20 g/s Operating Conditions: Engine running at idle, ECT sensor less than 60°C (140°F) Parameter Normal Range: 4,000-4,400 Hz and 30-40 g/s | |||
Ignition 1 Voltage | 65535 Hz | 65535 Hz | -- |
MAF Sensor Signal | 65535 Hz | 65535 Hz | 65535 Hz |
Low Reference | -- | -- | -- |
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:
• | A MAF sensor ignition 1 voltage circuit |
• | A MAF sensor ground circuit |
• | A MAF sensor signal circuit |
• | An IAT sensor signal circuit |
• | An IAT sensor 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 signal on the inlet airflow through the sensor bore. The frequency varies in a range depending on engine coolant temperature (ECT) sensor 1 of approximately 2,300 Hertz at idle to near 9,000 Hertz at maximum engine load.
When engine coolant temperatures reach 60°C (140°F) the ECM commands a Rich Idle mode. During Rich Idle the exhaust gas recirculation (EGR) valve is commanded ON, and a lower frequency and g/s value will be indicated on the scan tool.
• | The engine is running for greater than 2 seconds. |
• | The engine speed is between 500-3,100 RPM. |
• | The above conditions are met for more than 3 seconds. |
• | This DTC runs continuously within the enabling conditions. |
• | The engine is running for greater than 2 seconds |
• | The above conditions are met for greater than 3 seconds. |
• | This DTC runs continuously within the enabling conditions. |
The ECM detects that the MAF sensor is less than 3.6 g/s for greater than 3 seconds.
The ECM detects that the MAF sensor is greater than 527 g/s for greater than 3 seconds.
• | DTCs P0102 and P0103 are Type B DTCs. |
• | The ECM commands reduced engine power. |
• | The Diesel Particulate Filter (DPF) Regeneration is Inhibited. |
• | The driver information center (DIC) or indicator may display reduced engine power. |
DTCs P0102 and P0103 are Type B DTCs.
• | 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 10-40 g/s at idle to greater than 380 g/s at the time of the 1-2 shift. |
• | For an intermittent problem, visually and physically inspect the EGR valve for a possible binding or sticking in the open position. |
• | Verify that any electrical aftermarket devices are properly connected and grounded. Refer to Checking Aftermarket Accessories. |
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
J 38522 Variable Signal Generator
⇒ | If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle |
• | Damaged components |
• | Loose or improper installation |
• | Restrictions or leaks in the air induction system |
• | Water intrusion |
• | In cold climates, inspect for any snow or ice build-up. |
⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
⇒ | If greater than the specified range, test the IAT sensor low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
⇒ | If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. |
⇒ | If less than the specified range, test the MAF 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 MAF signal circuit for a short to voltage. If the circuit tests normal, replace the ECM. |
⇒ | If the EGR valve is not in the closed position, replace the EGR valve. |
⇒ | If the EGR valve inspection is normal, replace the MAF/IAT sensor. |
Important: You must perform the Circuit/System Testing in order to verify the integrity of the MAF sensor circuits before proceeding with the Component Testing.
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. |
• | Control Module References for ECM replacement, setup, and programming |