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Hummer H1 (2006+). Manual - part 58

OBD-76

On-Board Diagnostics

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Turn OFF the ignition.

Inspect for air leaks in the following components:

• The air induction system and the turbocharger system

• The charge air cooler with a J 46091 Charge Air Cooler

Tester

• The mass air flow (MAF)/intake air temperature (IAT)

sensor O-ring seal

• The boost pressure sensor seal

• An exhaust gas recirculation (EGR) valve gasket that is

missing or damaged

Inspect for the following conditions:

• A cracked MAF sensor housing

• An obstructed intake air duct or a dirty air filter element

• Any debris that is blocking the air sensing filaments of the

MAF sensor

• Any water intrusion in the air induction system

• A MAF sensor that is installed backwards

• An EGR valve that is stuck open

• A restricted exhaust system

Did you find and correct the condition?

Go to Step 24

Go to Step 6

Turn ON the ignition, with the engine OFF.

Observe both the BARO parameter and the Boost Pressure
Sensor parameter with a scan tool.

Is the difference between the sensors equal to or less than the
specified value?

5 kPa

Go to Step 8

Go to DTC

P2227

Disconnect the MAF/IAT sensor.

Observe the MAF Sensor parameter with a scan tool.

Is the MAF Sensor parameter more than the specified value?

0 V

Go to Step 14

Go to Step 8

Start the engine and allow it to idle.

Observe the MAF Sensor parameter with a scan tool.

Move the harness and the connector of the MAF/IAT sensor.

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

Go to Step 21

Go to Step 9

Turn OFF the engine.

Turn ON the ignition, with the engine OFF.

Measure the battery voltage with a DVOM.

Disconnect the MAF/IAT sensor.

Connect a test lamp between the ignition voltage circuit 239
(PK) of the MAF sensor and a good ground.

Connect the DVOM to the probe of the test lamp and a good
ground.

Is the voltage within 1.5 volts of the specified value?

B+

Go to Step 10

Go to Step 18

Step

Action

Value(s)

Yes

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On-Board Diagnostics OBD-77

5745804

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

Turn OFF the ignition for 60 seconds to allow the control
modules to power down before proceeding.

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 12

Turn ON the ignition, with the engine OFF.

Connect a 3-amp fused jumper wire between the signal cir-
cuit 654 (DB) of the MAF sensor and the signal circuit 653
(YL) of the IAT sensor.

Observe the MAF Sensor parameter with a scan tool.

Is the MAF Sensor parameter more than the specified value?

445 g/s

Go to Step 16

Go to Step 13

Disconnect the engine control module (ECM).

Test the MAF sensor low reference circuit 251 (BK) between
C76 pin 29 and pin 4 of the MAF sensor connector for the
following conditions between:

• A high resistance

• An intermittent open

Did you find and correct the condition?

Go to Step 24

Go to Step 17

Turn OFF the ignition.

Disconnect the ECM.

Test the MAF sensor signal circuit 654 (DB) between C75
pin 13 and the MAF sensor pin 5 for the following condi-
tions:

• A high resistance or an intermittent open

• A high resistance short to ground

• A high resistance short to the low reference circuit of the

MAF sensor or the IAT sensor

Did you find and correct the condition?

Go to Step 24

Go to Step 17

NOTE: Disconnecting the ECM connectors may eliminate the
short to voltage if the signal circuit is shorted to another ECM cir-
cuit.

Turn OFF the ignition.

Disconnect the ECM, C75 connector only.

Turn ON the ignition, with the engine OFF.

Measure the voltage from the signal circuit 654 (DB) of the
MAF sensor to a good ground with a DVOM.

Is the voltage more than the specified value?

0 V

Go to Step 19

Go to Step 15

Turn OFF the ignition.

Disconnect all of the ECM connectors.

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 20

Go to Step 17

Step

Action

Value(s)

Yes

OBD-78

On-Board Diagnostics

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Test for shorted terminals and for an intermittent and for a poor
connection at the MAF/IAT sensor.

Did you find and correct the condition?

Go to Step 24

Go to Step 22

Test for shorted terminals and for an intermittent and for a poor
connection at the ECM.

Did you find and correct the condition?

Go to Step 24

Repair the high resistance or the intermittent open in the MAF
sensor ignition voltage circuit 239 (PK).

Did you complete the repair?

Go to Step 24

Repair the short to voltage in the MAF sensor signal circuit 654
(DB).

Did you complete the repair?

Go to Step 24

Repair the circuits that are shorted together.

Did you complete the repair?

Go to Step 24

Repair the harness or the connections as necessary.

Did you complete the repair?

Go to Step 24

Replace the faulty MAF/IAT sensor.

Did you complete the replacement?

Go to Step 24

Replace the faulty ECM.

Did you complete the replacement?

Go to Step 24

Clear the DTCs with a scan tool.

Turn OFF the ignition for 30 seconds.

Start the engine.

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 25

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

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On-Board Diagnostics OBD-79

5745804

DTC P0102 Mass Air Flow (MAF) Sensor Performance (Figure OBD-24)

Figure OBD-24: 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 less than the possible range of a normally operat-
ing sensor DTC P0102 sets.

Conditions for Setting the DTC

The ECM detects that the MAF sensor voltage signal is less than 0.42 volt 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-
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.

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