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Hummer H2. Manual - part 1517

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

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. The PCM uses the following sensor inputs to
calculate a predicted MAF value:

The manifold absolute pressure (MAP) sensor

The intake air temperature (IAT) sensor

The engine coolant temperature (ECT) sensor

The engine speed in revolutions per minute (RPM)

The PCM compares the actual MAF sensor frequency signal to the predicted MAF value. This comparison will
determine if the signal is stuck based on a lack of variation, or is too low or too high for a given operating
condition. If the PCM detects the actual MAF sensor frequency signal is not within a predetermined range of
the calculated MAF value DTC P0101 sets.

Conditions for Running the DTC

DTCs P0102, P0103, P0106, P0107, P0108, P0120, P0220, P0442, P0443, P0446, P0449, P0455, P0496,
P2135 are not set.

The engine is cranking or running.

The ignition 1 signal is between 11-18 volts.

The throttle position (TP) indicated angle is less than 95 percent.

The change in the TP indicated angle is less than 5 percent.

The MAP sensor is more than 17 kPa.

The change in the MAP sensor is less than 3 kPa.

The above conditions are met for 1.5 seconds.

Conditions for Setting the DTC

The PCM detects that the actual MAF sensor frequency signal is not within a predetermined range of the
calculated MAF value for more than 4 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.

2004 Hummer H2

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

Hummer H2

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

{

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.

Inspect the air induction system for any water intrusion. Any water that reaches the MAF sensor will
skew the sensor and may cause this DTC to set.

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 ignition 1 voltage circuit may cause this DTC to set. A high
resistance may cause a driveability concern before this DTC sets.

The barometric pressure (BARO) that is used to calculate the predicted mass air flow value is initially
based on the MAP sensor at key ON. When the engine is running the BARO value is continually updated
near wide open throttle. A skewed MAP sensor will cause the calculated mass air flow value to be
inaccurate and may result in a no start condition. The value shown for the MAP sensor parameter varies
with the altitude. With the ignition ON and the engine OFF, 101 kPa is the approximate value near sea
level. This value will decrease by approximately 3 kPa for every 305 meters (1,000 feet) of altitude.

A high resistance on the 5-volt reference circuit of the MAP sensor may cause this DTC to set.

A high resistance on the low reference circuit of the MAP sensor may cause this DTC to set.

If the condition is intermittent, refer to Intermittent Conditions .

2004 Hummer H2

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

Hummer H2

Test Description

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

5: This step will determine if the MAP sensor pressure is within the proper range for a given altitude.

6: This step will determine if the MAP sensor voltage is within the proper range at idle.

7: This step will determine if the MAP sensor responds properly to the change in manifold pressure.

8: This step will determine if the TP sensors are operating properly.

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

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

DTC P0101 (With Throttle Actuator Control)

Step

Action

Values

Yes

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

Did you perform the Diagnostic System
Check-Engine Controls?

Go to Step 2

Go to

Diagnostic

System

Check -

Engine

Controls

Attempt to start the engine.
Does the engine start?

Go to Step 3

Go to Step 5

Observe the Diagnostic Trouble Code (DTC)
Information with the scan tool.
Does the scan tool display any other DTCs
set?

Go to Diagnostic Trouble

Code (DTC) List

Go to Step 4

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 5

Go to

Diagnostic

Aids

IMPORTANT:

The Altitude vs. Barometric Pressure table
indicates a pressure range for a given
altitude under normal weather conditions.
Weather conditions consisting of very low

2004 Hummer H2

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

Hummer H2

1. Turn ON the ignition, with the engine

OFF.

2. Observe the MAP sensor kPa parameter

with a scan tool.

3. The manifold absolute pressure (MAP)

sensor pressure should be within the
specified range for your altitude. Refer
to Altitude vs Barometric Pressure .

Is the MAP sensor pressure within the
specified range as indicated on the Altitude
Vs. Barometric Pressure table?

or very high pressure and/or temperature
may cause a reading to be slightly out of
range.

Go to Step 6

Go to DTC

P0106 (With

Throttle

Actuator

Control)

1. Start the engine.

2. Turn OFF all accessories.

3. Allow the engine to reach operating

temperature.

4. Observe the MAP sensor parameter

with a scan tool.

Is the MAP sensor parameter within the
specified range?

0.8-2.0

Go to Step 7

Go to DTC

P0106 (With

Throttle

Actuator

Control)

1. Idle the engine.

2. Observe the MAP sensor parameter

with a scan tool.

3. Increase the engine speed slowly to

3,000 RPM and then back to idle.

Does the MAP sensor parameter change
smoothly and gradually through the specified
range of the test?

Go to Step 8

Go to DTC

P0106 (With

Throttle

Actuator

Control)

1. Turn OFF the ignition for 30 seconds.

2. Turn ON the ignition with the engine

OFF.

3. Observe the throttle position (TP)

indicated angle parameter with a scan
tool.

4. Depress the accelerator pedal

completely.

98-

100%

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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