GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The mass air flow (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 voltage signal to provide the correct fuel delivery for a reduction in emissions. The ECM uses the MAF sensor signal to control fuel delivery until a calibrated amount of engine air flow is attained. The MAF sensor has an ignition 1 voltage circuit, a signal circuit and a low reference circuit. The MAF sensor produces an output voltage based on the inlet air flow through the air induction system. This output voltage will display on the scan tool as a voltage parameter and as a grams per second (g/s) parameter. If the ECM detects that the actual MAF sensor voltage signal is more than the possible range of a normally operating sensor DTC P0103 sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0103 Mass Air Flow (MAF) Sensor Circuit High Voltage.

Conditions for Running the DTC

    • DTC P0112, P0113 are not set.
    • The engine is running for more than 2 seconds.
    • The engine speed is between 500-2,500 RPM.
    • The ignition 1 signal is more than 9 volts.
    • The IAT Sensor parameter is more than -7°C (19°F).
    • The above conditions are met for more than 3 seconds.
    • DTC P0103 runs continuously within the enabling conditions.

Conditions for Setting the DTC

The ECM detects that the MAF sensor voltage signal is more than 4.5 volts for more than 6 seconds.

Action Taken When the DTC Sets

    • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

  1. Start the engine.
  2. Observe the MAF Sensor parameter with a scan tool.

Is the MAF Sensor parameter more than the specified value?

4.5 V

Go to Step 4

Go to Step 3

3

  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 4

Go to Inducing Intermittent Fault Conditions in Wiring Systems and Intermittent Conditions

4

  1. Allow the engine to idle.
  2. Observe the MAF Sensor parameter with a scan tool.
  3. Move the harness and the connector of the mass air flow (MAF)/intake air temperature (IAT) sensor.

Does the movement of the harness or the connector affect the MAF Sensor parameter?

--

Go to Step 14

Go to Step 5

5

  1. Observe the MAF Sensor parameter with a scan tool.
  2. Disconnect the MAF sensor.

Is the MAF Sensor parameter more than the specified value?

4.5 V

Go to Step 9

Go to Step 6

6

  1. Turn OFF the ignition.
  2. Inspection the air induction system for any water intrusion.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 7

7

Important: All electrical components and accessories must be turned OFF.

  1. Turn OFF the ignition for 60 seconds to allow the control modules to power down before proceeding.
  2. Measure the resistance from the low reference circuit of the MAF sensor to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.

Is the resistance less than the specified value?

5 ohms

Go to Step 11

Go to Step 8

8

  1. Disconnect the engine control module (ECM).
  2. Test the low reference circuit between the ECM and the MAF sensor for a high resistance or an open. Refer to Circuit Testing in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 12

9

Important:: Disconnecting the harness connectors of the ECM may eliminate the short to voltage if the signal circuit is shorted to another ECM circuit.

  1. Turn OFF the ignition.
  2. Disconnect the harness connectors of the ECM.
  3. Test the MAF sensor signal circuit for the following conditions:
  4. • A short to voltage
    • A short to any 5-volt reference circuit.
    •  Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 10

10

Measure the resistance from the signal circuit of the MAF sensor to all other circuits at all ECM connectors with a DMM. Refer to Circuit Testing in Wiring Systems.

Is the resistance less than the specified value?

∞ ohms

Go to Step 13

Go to Step 12

11

Test for an intermittent and for a poor connection at the MAF/IAT sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs and Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 15

12

Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs and Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 16

13

Repair the circuits that are shorted together. Refer to Wiring Repairs in Wiring Systems

Did you complete the repair?

--

Go to Step 17

--

14

Repair the harness or the connections as necessary. Refer to Wiring Repairs and Connector Repairs and Repairing Connector Terminals in Wiring Systems.

Did you complete the repair?

--

Go to Step 17

--

15

Replace the MAF/IAT sensor. Refer to Mass Airflow Sensor/Intake Air Temperature Sensor Replacement .

Did you complete the replacement?

--

Go to Step 17

--

16

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

--

Go to Step 17

--

17

  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 18

18

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK