GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 GMC C Sierra - 2WD 🢒 Engine 🢒 Engine Controls - 6.6L (LB7) 🢒 DTC P0102

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 grams per second (g/s) value. If the ECM detects that the actual MAF sensor voltage signal is less than the possible range of a normally operating sensor DTC P0102 sets.

Conditions for Running the DTC
    • The engine is running for more than 2 seconds.
    • The engine speed is more than 500 RPM.
    • The ignition 1 signal is more than 9 volts.
    • The above conditions are present for more than 2 seconds.

Conditions for Setting the DTC
    • The ECM detects that the MAF sensor signal is less than 0.5 volt. This equals a MAF value of less than 16 g/s.
    • The condition is met for more than 2 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.

Diagnostic Aids

Inspect for the following conditions:

    • Any unmetered air--Any unmetered air that enters the engine downstream of the MAF sensor may cause this DTC to set.
    • A sluggish or unresponsive MAF sensor--A short between the signal circuit of the MAF sensor and the signal circuit of the intake air temperature (IAT) sensor. This will cause the MAF sensor to have a very limited output voltage range.
    • Any debris that may be blocking the sensing elements of the MAF sensor
    • Any water in the air induction system
    • The MAF display should increase from 42-50 g/s at idle to 420 g/s or more at the 2-3 shift during a wide-open throttle (WOT) acceleration. If not, inspect for a restriction in the induction system or the exhaust system.
    • If the condition is intermittent, refer to Intermittent Conditions .

Test Description

The number below refers to the step number on the diagnostic table.

  1. A short to another ECM-controlled circuit may not be present when the ECM is disconnected as part of the previous test. A short across two ECM circuits can cause this DTC to set.

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. Monitor the Diagnostic Trouble Code (DTC) information using the scan tool.

Does the scan tool display any other DTCs set?

--

Go to Diagnostic Trouble Code (DTC) List

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 Diagnostic Aids

4

Inspect the fuse in the ignition 1 voltage circuit of the mass air flow (MAF) sensor.

Is the fuse open?

--

Go to Step 9

Go to Step 5

5
  1. Turn OFF the ignition.
  2. Inspect for air leaks in the following components:
    3. • A damaged MAF sensor housing
    • The air induction system and the turbocharger system
    • The MAF sensor O-ring seal
    • The boost pressure sensor seal
  3. Inspect for the following conditions:
    4. • An obstructed intake air duct or a dirty air filter element
    • Any debris that is blocking the air sensing filaments of the MAF sensor
    • A MAF sensor that is installed backwards
    • A restricted exhaust system--Refer to Restricted Exhaust in Engine Exhaust.

Did you find and correct the condition?

--

Go to Step  20

Go to Step 6

6
  1. Start the engine and allow the engine to idle.
  2. Observe the MAF Sensor parameter with a scan tool.
  3. Move the harness and the connector of the MAF sensor.

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

--

Go to Step 15

Go to Step 7

7
  1. Turn OFF the engine.
  2. Turn ON the ignition, with the engine OFF.
  3. Disconnect the harness connector of the MAF sensor.
  4. Connect a test lamp between the ignition 1 voltage circuit of the MAF sensor and a good ground. Refer to Circuit Testing in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 8

Go to Step 13

8
  1. Connect a 3-amp fused jumper wire between the signal circuit of the intake air temperature (IAT) sensor and the signal circuit of the MAF sensor. Refer to Circuit Testing in Wiring Systems.
  2. Observe the MAF Sensor parameter with a scan tool.

Did the MAF Sensor parameter change to the specified value?

445 g/s

Go to Step 16

Go to Step 10

9

Test for continuity between the ignition 1 voltage circuit of the MAF sensor and ground with a DMM. Refer to Circuit Testing in Wiring Systems.

Does the DMM indicate continuity?

--

Go to Step 12

Go to Step  16

10
  1. Turn OFF the ignition.
  2. Disconnect the fused jumper wire.
  3. Disconnect the engine control module (ECM).
  4. Test the signal circuit between the ECM and the MAF sensor for the following conditions:
    5. • A high resistance or an open
    • A short to ground
    • A short to the low reference circuit of the MAF sensor or IAT sensor--Refer to Circuit Testing in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 11

11

Test for continuity at the harness connector of the ECM from the signal circuit of the MAF sensor to all other circuits at both ECM connectors with a DMM. Refer to Circuit Testing in Wiring Systems.

Does the DMM indicate continuity between any other circuit?

--

Go to Step 14

Go to Step 17

12
  1. Repair the short to ground in the ignition 1 voltage circuit of the MAF sensor. Refer to Wiring Repairs in Wiring Systems.
  2. Replace the fuse as needed.

Did you complete the repair?

--

Go to Step 20

--

13

Repair the open in the ignition 1 voltage circuit of the MAF sensor. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 20

--

14

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

Did you complete the repair?

--

Go to Step 20

--

15

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

Did you complete the repair?

--

Go to Step  20

--

16

Inspect for poor connections at the harness connector of the MAF sensor. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 18

17

Inspect for poor connections at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 19

18

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

Did you complete the replacement?

--

Go to Step 20

--

19

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

--

Go to Step 20

--

20
  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 21

21

With a scan tool observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK