Hummer H1 (2006+). Manual — part 60

OBD-84

On-Board Diagnostics

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DTC P0103 Mass Air Flow (MAF) Sensor Ckt High Voltage (Figure OBD-25)

Figure OBD-25: Mass Air Flow (MAF) Sensor Circuit

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 mod-
ule (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 operat-
ing sensor DTC P0103 sets.

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 diag-

nostic 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 consecu-

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On-Board Diagnostics OBD-85

5745804

tive 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

Value(s)

Yes

No

1

NOTE: Before clearing DTC(s) use the scan tool “Capture info”
to record Freeze Frame and Failure Records for reference, as data
will be lost when “Clear Info” function is used

Was the “On-Board Diagnostic (OBD) System Check” per-
formed?

Go to step 2.

Go to OBD Sys-

tem Check.

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 Diagnos-

tic Aids

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

NOTE: 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 251
(BK) of the MAF sensor to a good ground with a DVOM.

Is the resistance less than the specified value?

5 ohms

Go to Step 11

Go to Step 8

OBD-86

On-Board Diagnostics

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8

NOTE: Disconnecting the harness connectors of the ECM may
eliminate the short to voltage if the signal circuit is shorted to an-
other ECM circuit.

1.

Turn OFF the ignition.

2.

Disconnect the ECM connectors.

3.

Test the MAF sensor signal circuit 654 (DB) for the follow-
ing conditions:

• A short to voltage.

• A short to any 5-volt reference circuit.

Did you find and correct the condition?

Go to Step 17

Go to Step 10

9

NOTE: Disconnecting the harness connectors of the ECM may
eliminate the short to voltage if the signal circuit is shorted to an-
other ECM circuit.

1.

Turn OFF the ignition.

2.

Disconnect the harness connectors of the ECM.

3.

Test the MAF sensor signal circuit 654 (DB) for the follow-
ing conditions:

• A short to voltage

• A short to any 5-volt reference circuit.

Did you find and correct the condition?

Go to Step 17

Go to Step 10

10

Measure the resistance from the signal circuit 654 (DB) of the
MAF sensor to all other circuits at all ECM connectors with a
DVOM.

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.

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.

Did you find and correct the condition?

Go to Step 17

Go to Step 16

13

Repair the circuits that are shorted together.

Did you complete the repair?

Go to Step 17

14

Repair the harness or the connections as necessary.

Did you complete the repair?

Go to Step 17

15

Replace the faulty MAF/IAT sensor.

Did you complete the replacement?

Go to Step 17

16

Replace the faulty ECM.

Did you complete the replacement?

Go to Step 17

Step

Action

Value(s)

Yes

No

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On-Board Diagnostics OBD-87

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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

1.

Using the Scan Tool select “Capture Info,” Review Info.” Are
any DTC’s displayed that have not been diagnosed?

Go to the appli-

cable DTC

table.

System OK.

Step

Action

Value(s)

Yes

No