Hummer H2. Manual — part 1619

3

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

1. Observe the MAF Sensor parameter with a

scan tool.

2. 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 20

Go to Step 5

5

1. Turn OFF the ignition.

2. Inspect for the following conditions:

z

A restricted or collapsed air intake duct

z

A misaligned air intake duct

z

A dirty or deteriorating air filter element

z

Any objects blocking the air inlet screen
of the MAF/IAT sensor

z

Any water intrusion in the Induction
System

z

Any contamination or debris on the
sensing elements of the MAF sensor

Did you find and correct the condition?

-

Go to Step 28

Go to Step 6

6

Inspect the fuse in the ignition 1 voltage circuit of the
MAF sensor.
Is the fuse open?

-

Go to Step 14

Go to Step 7

7

1. Turn ON the ignition, with the engine OFF.

2. Measure the battery voltage with a DMM.

3. Disconnect the MAF/IAT sensor.

4. Connect a test lamp between the ignition 1

voltage circuit of the MAF sensor and a good
ground. Refer to Probing Electrical
Connectors in Wiring Systems.

B+

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L -

Hummer H2

5. Connect the DMM to the probe of the test

lamp and a good ground. Refer to Measuring
Voltage Drop and Circuit Testing in Wiring
Systems.

Is the voltage within 0.50 volts of the specified
value?

Go to Step 8

Go to Step 21

8

1. Turn OFF the ignition for 60 seconds to allow

the control modules to power down.

2. Measure the resistance from the ground 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?

IMPORTANT:

All electrical components and accessories must
be turned OFF.

5 ohm

Go to Step 9

Go to Step 22

9

1. Turn ON the ignition, with the engine OFF.

2. Measure the voltage from the signal circuit of

the MAF sensor to a good ground with a
DMM. Refer to Circuit Testing in Wiring
Systems.

Is the voltage within the specified range?

4.8-5.2

V

Go to Step 10

Go to Step 13

10

1. Connect a 3-amp fused jumper wire between

the signal circuit of the MAF sensor and a
good ground. Refer to Circuit Testing in
Wiring Systems.

2. Start the engine.

3. Observe the DTC Information with a scan tool.

Do any additional DTCs set?

-

Go to Step 24

Go to Step 11

1. Turn OFF the ignition.

2. Connect the voltage supply and the ground

lead of the J 38522 Variable Signal Generator
to the vehicle.

3. Connect the red lead of the J 38522 to the

signal circuit of the MAF sensor. Refer to
Probing Electrical Connectors in Wiring
Systems.

4. Set the Duty Cycle switch of the J 38522 to

4,950-

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L -

Hummer H2

11

Normal.

5. Set the Frequency switch of the J 38522 to 5

K.

6. Set the Signal switch of the J 38522 to 5 V.

7. Start the engine and allow it to idle.

8. Observe the MAF Sensor parameter with a

scan tool.

Is the MAF Sensor parameter within the specified
range?

5,025

Hz

Go to Step 12

Go to Step 15

12

1. Turn OFF the ignition.

2. Disconnect the powertrain control module

(PCM).

3. Test the MAF sensor signal circuit for a high

resistance and for a short to the IAT signal
circuit. Refer to Circuit Testing and Wiring
Repairs in Wiring Systems.

Did you find and correct the condition?

IMPORTANT:

An abnormal resistance on the signal circuit
will disable the MAF sensor frequency
before the voltage starts to drop out of the
correct parameter of 4.8-5.2 volts.

-

Go to Step 28

Go to Step 18

13 Is the voltage less than the specified value?

4.8 V

Go to Step 15

Go to Step 16

14

Test the ignition 1 voltage circuit for a short to
ground. Refer to Testing for Short to Ground and
Wiring Repairs in Wiring Systems.Did you find and
correct the condition?

IMPORTANT:

The ignition 1 voltage circuit of the MAF sensor is
spliced to other components of the vehicle.

-

Go to Step 28

-

15

1. Turn OFF the ignition.

2. Disconnect the PCM.

3. Test the signal circuit between the PCM and

the MAF sensor for the following conditions:

z

A high resistance

z

An open circuit

z

A short to ground

Refer to Circuit Testing and Wiring Repairs in

-

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L -

Hummer H2

Wiring Systems.Did you find and correct the
condition?

Go to Step 28

Go to Step 17

16

1. Turn OFF the ignition.

2. Disconnect the PCM.

3. Turn ON the ignition, with the engine OFF.

4. Measure the voltage from the signal circuit of

the MAF sensor to a good ground with a
DMM. Refer to Circuit Testing in Wiring
Systems.

Is the voltage more than the specified value?

IMPORTANT:

Disconnecting the PCM connectors may eliminate
the short to voltage if the signal circuit is shorted
to another PCM circuit.

0 V

Go to Step 23

Go to Step 17

17

Measure the resistance from the signal circuit of the
MAF sensor to all other circuits at both PCM
connectors with a DMM. Refer to Circuit Testing in
Wiring Systems.
Is the resistance less than the specified value?

infinity

ohm

Go to Step 25

Go to Step 19

18

Test for an intermittent and for a poor connection at
the MAF sensor. Refer to Testing for Intermittent
Conditions and Poor Connections and Connector
Repairs in Wiring Systems.
Did you find and correct the condition?

-

Go to Step 28

Go to Step 26

19

Test for an intermittent and for a poor connection at
the PCM. Refer to Testing for Intermittent
Conditions and Poor Connections and Connector
Repairs in Wiring Systems.
Did you find and correct the condition?

-

Go to Step 28

Go to Step 27

20

Repair the wiring or the connector as needed. Refer
to Wiring Repairs and Connector Repairs in
Wiring Systems.
Did you complete the repair?

-

Go to Step 28

-

21

Repair the high resistance or the open in the MAF
sensor ignition 1 voltage circuit. Refer to Wiring
Repairs in Wiring Systems.
Did you complete the repair?

-

Go to Step 28

-

22

Repair the high resistance or the open in the MAF
sensor ground circuit. Refer to Wiring Repairs in
Wiring Systems.
Did you complete the repair?

-

Go to Step 28

-

23

Repair the short to voltage in the MAF sensor signal
circuit. Refer to Wiring Repairs in Wiring Systems.

-

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L -

Hummer H2