Hummer H1 (2006+). Manual — part 137
OBD-392
On-Board Diagnostics
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DTC P1123, P1226, P1229, P1232, P1235, P1238, P1241, P1244 Injector Output Circuit (Figure
OBD-102)
Figure OBD-102: Injector Output Circuit
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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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