Hummer H1 (2006+). Manual — part 150

OBD-444

On-Board Diagnostics

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DTC P2228 Barometric Pressure (BARO) Sensor Circuit Low Voltage (Figure OBD-114)

Figure OBD-114: Barometric Pressure (BARO) Sensor Circuit

Circuit Description

The barometric pressure (BARO) sensor measures the pressure of the atmosphere. This pressure is affected by altitude and weather
conditions. A diaphragm within the BARO sensor is displaced by the pressure changes that occur from varying altitudes and
weather conditions. The sensor translates this action into electrical resistance. The BARO sensor wiring includes 3 circuits. The en-
gine control module (ECM) supplies a regulated 5 volts to the sensor on a 5-volt reference circuit. The ECM supplies a ground on
a low reference circuit. The BARO sensor provides a signal voltage to the ECM, relative to the pressure changes on the BARO sen-
sor signal circuit. The ECM converts the signal voltage input to a pressure value.

Changes in BARO due to weather are relatively small, while changes due to altitude are significant. Pressure can range from 56
kPa at an altitude of 4 267 meters (14,000 feet), to 105 kPa at or below sea level. The BARO sensor has a range of 8-207 kPa. The
ECM uses the BARO sensor input for fuel delivery and other diagnostics.

The ECM monitors the BARO sensor signal for pressure outside of the normal range. If the ECM detects a BARO sensor pressure
that is excessively low, DTC P2228 sets.

Conditions for Setting the DTC

The BARO is less than 40 kPa for 10 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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On-Board Diagnostics OBD-445

5745804

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.

ALTITUDE MEASURED

IN METERS (M)

ALTITUDE MEASURED

IN FEET (FT)

BAROMETRIC PRESSURE

MEASURED IN KILOPASCALS (KPA)

4 267

14,000

56-64

3 962

13,000

58-66

3 658

12,000

61-69

3 353

11,000

64-72

3 048

10,000

66-74

2 743

9,000

69-77

2 438

8,000

71-79

2 134

7,000

74-82

1 829

6,000

77-85

1 524

5,000

80-88

1 219

4,000

83-91

914

3,000

87-95

610

2,000

90-98

305

1,000

94-102

0

0 Sea Level

96-104

-305

-1,000

101-105

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnos-

tic System

Check

2

1.

Start the engine.

2.

Monitor the Diagnostic Trouble Code (DTC) Information
with a scan tool.

Does the scan tool indicate that DTC P0652 is also set?

Go to DTC

P0652

Go to Step 3

3

Observe the BARO parameter with a scan tool.

Does the scan tool indicate that the pressure is less than the spec-
ified value?

40 kPa

Go to Step 5

Go to Step 4

OBD-446

On-Board Diagnostics

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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 Intermit-

tent Conditions

5

1.

Turn OFF the ignition.

2.

Disconnect the barometric pressure (BARO) sensor electrical
connector.

3.

Turn ON the ignition, with the engine OFF.

4.

Measure the voltage from the 5-volt reference circuit 612
(WH/BK) of the BARO sensor to a good ground, with a
DVOM.

Is the voltage more than the specified value?

4.8 Volts

Go to Step 6

Go to Step 7

6

Connect a 3-amp fused jumper wire between the 5-volt reference
circuit 612 WH/BK) of the BARO sensor and the signal circuit
613 (GY/BK) of the BARO sensor.

Does the scan tool indicate that the BARO sensor pressure is
more than the specified value?

205 kPa

Go to Step 9

Go to Step 8

7

Test the 5-volt reference circuit 612 WH/BK) of the BARO sen-
sor for an open.

Did you find and correct the condition?

Go to Step 13

Go to Step 10

8

Test the signal circuit of the BARO sensor for the following:

• A short to ground

• A short to low reference

• An open

Did you find and correct the condition?

Go to Step 13

Go to Step 10

9

Inspect for poor connections at the BARO sensor.

Did you find and correct the condition?

Go to Step 13

Go to Step 11

10

Inspect for poor connections at the engine control module
(ECM).

Did you find and correct the condition?

Go to Step 13

Go to Step 12

11

Replace the faulty BARO sensor.

Did you complete the replacement?

Go to Step 13

12

Replace the faulty ECM.

Did you complete the replacement?

Go to Step 13

13

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 14

Step

Action

Value(s)

Yes

No

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On-Board Diagnostics OBD-447

5745804

14

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnos-

tic Trouble

Code

System OK

Step

Action

Value(s)

Yes

No