Hummer H1 (2006+). Manual - part 148

OBD-436

On-Board Diagnostics

_____________________________________________

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

Is DTC P2138 also set?

Go to DTC 

P2138

Go to Step 3 

    3

Is DTC P2139 also set?

Go to DTC 

P2139

_____________________________________________

 On-Board Diagnostics  OBD-437

5745804

DTC P2146 Injector Positive Voltage Control Circuit Group1

Circuit Description

The fuel injection control module (FICM) supplies high voltage to each fuel injector on the ignition voltage circuits. The FICM en-
ergizes each fuel injector by grounding the command circuit between the FICM and the fuel injector. The FICM monitors the status
of the ignition voltage circuits and the fuel injector command circuits. When a fuel injector circuit condition is detected by the
FICM, all of the fuel injectors on the affected ignition voltage circuit will be disabled. If a circuit condition is detected on a fuel in-
jector circuit for cylinders 1, 4, 6, or 7, DTCs P0201, P0204, P0206, P0207 will set, along with DTC P2146. If a circuit condition
is detected on a fuel injector circuit for cylinders 2, 3, 5, or 8, DTCs  P0202, P0203, P0205, P0208 will set, along with DTC P2149.

Conditions for Setting the DTC

The engine control module (ECM) detects a circuit fault related to the high voltage circuit to cylinders 1, 4, 6, and 7.

Action Taken When the DTC Sets 

• The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. 

• The control module records the operating conditions at the time the diagnostic fails. The control module stores this informa-

tion in the Freeze Frame/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. 

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

Is DTC P0201, P0204, P0206, or P0207 also set?

Go to DTC 

P0201-P0208

Go to Step 3 

    3

Replace the faulty fuel injection control module (FICM). 

Did you complete the replacement?

Go to Step 4

    4

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 5

    5

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

OBD-438

On-Board Diagnostics

_____________________________________________

DTC P2149 Injector Positive Voltage Control Circuit Group 2

Circuit Description

The fuel injection control module (FICM) supplies high voltage to each fuel injector on the ignition voltage circuits. The FICM en-
ergizes each fuel injector by grounding the command circuit between the FICM and the fuel injector. The FICM monitors the status
of the ignition voltage circuits and the fuel injector command circuits. When a fuel injector circuit condition is detected by the
FICM, all of the fuel injectors on the affected ignition voltage circuit will be disabled. If a circuit condition is detected on a fuel in-
jector circuit for cylinders 1, 4, 6, or 7, DTCs P0201, P0204, P0206, P0207 will set, along with DTC P2146. If a circuit condition
is detected on a fuel injector circuit for cylinders 2, 3, 5, or 8, DTCs  P0202, P0203, P0205, P0208 will set, along with DTC P2149.

Conditions for Setting the DTC

The engine control module (ECM) detects a circuit fault related to the high voltage circuit to cylinders 2, 3, 5, and 8.

Action Taken When the DTC Sets 

• The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. 

• The control module records the operating conditions at the time the diagnostic fails. The control module stores this informa-

tion in the Freeze Frame/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. 

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

Is DTCs P0202, P0203, P0205, or P0208 also set?

Go to DTC 

P0201-P0208

Go to Step 3 

    3

Replace the faulty fuel injection control module (FICM). 

Did you complete the replacement?

Go to Step 4

    4

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 5

    5

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

_____________________________________________

 On-Board Diagnostics  OBD-439

5745804

DTC P2227 Barometric Pressure (BARO) Sensor Performance (Figure OBD-113)

Figure OBD-113:   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.

Within the ECM, the diagnostic compares the BARO sensor input to the boost pressure sensor input. If the ECM detects that the in-
puts are not within a specified amount of each other, DTC P2227 sets.

Conditions for Setting the DTC

The ECM detects that the difference between the BARO pressure and the boost pressure is more than 15 kPa for 6 seconds.