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Hummer H2. Manual - part 1618

Is the TP indicated angle parameter within the
specified range?

Go to Step 9

Go to DTC

P0120

1. Turn OFF the ignition.

2. Inspect for the following conditions:

A restricted or collapsed air
intake duct

A misaligned air intake duct

A dirty or deteriorating air filter
element

Any objects blocking the air inlet
screen of the mass air flow
(MAF) sensor, if equipped

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

Any water intrusion in the
induction system

Any vacuum leak downstream of
the MAF sensor

A MAF sensor wiring harness
that is routed too close to any
aftermarket accessories-Refer to
Checking Aftermarket
Accessories in Wiring Systems.

Any type of restriction in the
exhaust system

Did you find and correct the condition?

Go to Step 14 Go to Step 10

1. Disconnect the harness connector of the

MAF sensor.

2. Measure the battery voltage with a

DMM.

3. Turn ON the ignition, with the engine

OFF.

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.

5. Connect a DMM to the probe of the test

lamp and a good ground. Refer to
Measuring Voltage Drop 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

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
powertrain control module (PCM) uses the MAF sensor signal to provide the correct fuel delivery for all engine
speeds and loads. A small quantity of air entering the engine indicates a deceleration or idle condition. A large
quantity of air entering the engine indicates an acceleration or high load condition. The MAF sensor has the
following circuits:

An ignition 1 voltage circuit

A ground circuit

Is the voltage within 0.50 volts of the
specified value?

Go to Step 11 Go to Step 12

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 14 Go to Step 13

Repair the high resistance 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 14

Replace the MAF/intake air temperature (IAT)
sensor. Refer to Mass Air Flow
(MAF)/Intake Air Temperature (IAT)
Sensor Replacement .
Did you complete the replacement?

Go to Step 14

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 15

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

2004 Hummer H2

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

Hummer H2

A signal circuit

The PCM applies a voltage to the sensor on the signal circuit. The sensor uses the voltage to produce a
frequency based on the inlet air flow through the sensor bore. The frequency varies within a range of near 2,000
Hertz at idle to near 10,000 Hertz at maximum engine load. If the PCM detects the frequency signal is less than
the possible range of a correctly operating MAF sensor DTC P0102 sets.

Conditions for Running the DTC

The engine is running for more than 2 seconds.

The engine speed is more than 400 RPM.

The ignition 1 signal is more than 8 volts.

The MAF sensor frequency is stable for more than 1 second.

Conditions for Setting the DTC

The PCM detects that the MAF sensor frequency signal is less than 1,200 Hz for more than 0.6 second.

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 the harness of the MAF sensor to verify that it is not routed too close to the following
components:

{

The secondary ignition wires or coils

{

Any solenoids

{

Any relays

2004 Hummer H2

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

Hummer H2

{

Any motors

A low minimum air rate through the sensor bore at idle or during deceleration may cause this DTC to set.
Inspect for any vacuum leak downstream of the MAF sensor.

Inspect for any contamination or debris on the sensing elements of the MAF sensor.

A wide open throttle acceleration from a stop should cause the MAF sensor parameter on the scan tool to
increase rapidly. This increase should be from 3-10 g/s at idle to 170 g/s or more at the time of the 1-2
shift. If the increase is not observed, inspect for a restriction in the induction system or the exhaust
system.

A high resistance of 15 ohms or more on the ground circuit of the MAF sensor may cause this DTC to
set. A high resistance may cause a driveability concern before this DTC sets.

A high resistance of 15 ohms or more on the ignition 1 voltage circuit can cause this DTC to set. A high
resistance may cause a driveability concern before this DTC sets.

If the condition is intermittent, refer to Intermittent Conditions .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

5: This step will determine if any mechanical faults have caused this DTC to set.

7: This voltage drop test will determine if high resistance has caused this DTC to set.

9: This step verifies the voltage signal from the PCM to the MAF sensor connector.

10: This step tests the signal circuit of the MAF sensor for a short to another 5-volt reference circuit.

11: This step will determine if the PCM is able to process the frequency signal that it receives from the
MAF sensor.

14: This step will determine which portion of the circuit or which component is shorted to ground.

17: This step verifies that the signal circuit is not shorted to any other PCM circuit.

DTC P0102

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End Views or Powertrain Control
Module (PCM) Connector End Views

Did you perform the Diagnostic System Check-
Engine Controls?

Go to Step 2

Go to Diagnostic

System Check -

Engine Controls

1. Start the engine.

2. Observe the MAF Sensor parameter with a

scan tool.

Is the MAF Sensor parameter less than the specified
value?

1,200

Go to Step 4

Go to Step 3

1. Observe the Freeze Frame/Failure Records for

2004 Hummer H2

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

Hummer H2

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