Hummer H1 (2006+). Manual - part 137

 

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Hummer H1 (2006+). Manual - part 137

 

 

OBD-392

On-Board Diagnostics

_____________________________________________

DTC P1123, P1226, P1229, P1232, P1235, P1238, P1241, P1244 Injector Output Circuit (Figure 
OBD-102)

Figure OBD-102:   Injector Output Circuit

_____________________________________________

 On-Board Diagnostics  OBD-393

5745804

Circuit Description

The engine control module (ECM) enables the appropriate fuel injector on the compression stroke for each cylinder. The ECM
controls the fuel injection control module (FICM) by grounding the control circuit via a solid state device called a driver. The ECM
monitors the state of the driver. If the ECM detects an incorrect voltage for the commanded state of an injector driver, DTCs
P1223, P1226, P1229, P1232, P1235, P1238, P1241, or P1244 will set.

Conditions for Setting the DTC 

• The ECM detects that the commanded state and the actual state of the control circuit does not match. 

• The condition exists for less than 1 second. 

Action Taken When the DTC Sets 

• The control module stores the DTC information into memory when the diagnostic runs and fails. 

• The malfunction indicator lamp (MIL) will not illuminate. 

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

tion in the Failure Records. 

• The driver information center, if equipped, may display a message. 

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?

    2

1.

Start and idle the engine.

2.

Monitor the DTC Failed This Ignition parameter with a scan 
tool.

Do any of the DTCs P1223-1244 fail this ignition?

Go to Step 4 

Go to Step 3

    3

1.

Observe the Freeze Frame/Failure Records for this DTC 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.

Does the DTC fail this ignition?

Go to Step 4 

Go to Intermit-

tent Conditions 

    4

Are DTC P1223, P1232, P1238, and P1241 all set?

Go to Step 9 

Go to Step 5

    5

Are DTC P1226, P1229, P1235, and P1244 all set?

Go to Step 9 

Go to Step 6

OBD-394

On-Board Diagnostics

_____________________________________________

    6

1.

Turn OFF the ignition.

2.

Disconnect the harness connector C86 of the fuel injection 
control module (FICM). 

NOTE: Use the J 35616-94 Connector Adapter of the J 35616 to
probe the FICM connector.

3.

While cranking the engine, measure the frequency of the 
appropriate fuel injector control circuit with a DVOM. 

Is the voltage frequency more than the specified value?

2.9 Hz

Go to Step 12

Go to Step 7

    7

1.

Turn OFF the ignition.

2.

Disconnect harness connector C87 of the engine control 
module (ECM).

3.

Test the appropriate fuel injector control circuit for an open 
or short to another affected fuel injector control circuit. 

Did you find and correct the condition?

Go to Step 16

Go to Step 8

    8

1.

Turn OFF the ignition.

2.

Verify the harness connector C87 of the ECM is still discon-
nected.

3.

Probe the affected fuel injector control circuits with a test 
lamp connected to battery voltage. 

Does the test lamp illuminate on any of the fuel injector control
circuits?

Go to Step 10

Go to Step 15

    9

1.

Turn OFF the ignition.

2.

Disconnect the harness connector C87 of the ECM.

3.

Turn ON the ignition, with the engine OFF.

4.

Measure the voltage from each of the fuel injector control 
circuits with a DVOM. 

Is the voltage more than the specified value on any of the fuel in-
jector control circuits?

1 V

Go to Step 11

Go to Step 15

    10

Test the appropriate fuel injector control circuit for a short to
ground.

Did you find and correct the condition?

Go to Step 16

Go to Step 13

    11

Test the appropriate fuel injector control circuit for a short to
voltage.

Did you find and correct the condition?

Go to Step 16

Go to Step 14

    12

Inspect for poor connections at the harness connector of the
FICM.

Did you find and correct the condition?

Go to Step 16

Go to Step 14

    13

Inspect for poor connections at the harness connector of the
ECM.

Did you find and correct the condition?

Go to Step 16

Go to Step 15

    14

Replace the faulty FICM.  

Did you complete the replacement?

Go to Step 16

    15

Replace the faulty ECM.

Did you complete the replacement?

Go to Step 16

Step

Action

Value(s)

Yes

No

_____________________________________________

 On-Board Diagnostics  OBD-395

5745804

    16

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 17

    17

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnos-

tic Trouble 

Code (DTC) 

List

System OK

Step

Action

Value(s)

Yes

No

 

 

 

 

 

 

 

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