Hummer H1 (2006+). Manual - part 81

 

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Hummer H1 (2006+). Manual - part 81

 

 

OBD-168

On-Board Diagnostics

_____________________________________________

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

NOTE: Before clearing DTC(s) use the scan tool “Capture info”
to record Freeze Frame and Failure Records for reference, as data
will be lost when “Clear Info” function is used 

Was the “On-Board Diagnostic (OBD) System Check” per-
formed?

Go to step 2.

Go to OBD Sys-

tem Check.

    2

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 cycle?

Go to Step 3 

Go to Intermit-

tent Conditions 

    3

1.

Turn OFF the ignition for 30 seconds.

2.

Disconnect the exhaust gas recirculation (EGR) valve.

3.

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 DTC P0403 fail this ignition?

Go to Step 4 

Go to Step 6 

    4

NOTE: The low control circuit of the EGR valve normally has
near ignition voltage present. Test the low control circuit for a
short to all other voltage circuits from the engine control module
(ECM).

Test the low control circuit of the EGR valve for a short to volt-
age.

Did you find and correct the condition?

Go to Step 10 

Go to Step 7 

    5

Test the EGR motor high control circuits 108/110 (OR/BK and
low control circuits 109/111 (LG/BK) for a short to ground. 

Did you find and correct the condition?

Go to Step 10 

Go to Step 7 

    6

Test for shorted terminals and poor connections at the EGR
valve.

Did you find and correct the condition?

Go to Step 10

Go to Step 8

    7

Test for shorted terminals and poor connections at the ECM. 

Did you find and correct the condition?

Go to Step 10

Go to Step 9 

    8

Replace the faulty EGR valve. 

Did you complete the replacement?

Go to Step 10

_____________________________________________

 On-Board Diagnostics  OBD-169

5745804

    9

Replace the faulty ECM. 

Did you complete the replacement?

Go to Step 10

    10

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 11

   11

1.

Using the Scan Tool select “Capture Info,” Review Info.” Are 
any DTC’s displayed that have not been diagnosed?

Go to the appli-

cable DTC 

table.

System OK.

Step

Action

Value(s)

Yes

No

OBD-170

On-Board Diagnostics

_____________________________________________

DTC P0404 Exhaust Gas Recirculation (EGR) Open Position Performance (Figure OBD-49)

Figure OBD-49:   Exhaust Gas Recirculation (EGR) Position Sensor Circuit

Circuit Description

The engine control module (ECM) uses the exhaust gas recirculation (EGR) position sensor to determine the position of the EGR
valve. The ECM sends a reference voltage through the 5-volt reference circuit to the EGR position sensor. The ECM provides a
voltage return path for the sensor through the low reference circuit. A variable voltage signal, based on the EGR valve position, is
sent from the sensor to the ECM through the EGR position sensor signal circuit. The ECM compares the actual EGR position with
the desired EGR position when the EGR valve is commanded open or closed. If the ECM detects a variance between the actual
EGR position and desired EGR position for a calibrated amount of time while the EGR valve is commanded open, DTC P0404
sets.

Conditions for Setting the DTC 

• The difference between the actual EGR position and the desired EGR position is more than 6 percent. 

• The above condition is present for more than 5 seconds 

Action Taken When the DTC Sets - California 

• 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. 

_____________________________________________

 On-Board Diagnostics  OBD-171

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. 

Step

Action

Value(s)

Yes

No

    1

NOTE: Before clearing DTC(s) use the scan tool “Capture info”
to record Freeze Frame and Failure Records for reference, as data
will be lost when “Clear Info” function is used 

Was the “On-Board Diagnostic (OBD) System Check” per-
formed?

Go to step 2.

Go to OBD Sys-

tem Check.

    2

NOTE: Attaching the shop exhaust system to the vehicle may
cause false exhaust gas recirculation (EGR) DTCs to set. 

NOTE: Performing the EGR Solenoid output control function
may result in setting exhaust gas recirculation (EGR) system
DTCs.

1.

Start the engine.

2.

.Observe the EGR Position Variance parameter while com-
manding the exhaust gas recirculation (EGR) valve from 0-
30 percent with a scan tool.

3.

Exit the EGR output control function.

Did the EGR Position Variance parameter read more than the
specified value when commanded with a scan tool?

6%

Go to Step 4

Go to Step 3

    3

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 cycle?

Go to Step 4

Intermittent Go 

To Diagnostic 

Aids

    4

Is DTC P0403, P0405, or P0406 also set?

Go to  P0403 
Go to  P0405 
Go to  P0406 

Go to Step 5

    5

Test for shorted terminals and poor connections at the EGR
valve.

Did you find and correct the condition?

Go to Step 16

Go to Step 6

 

 

 

 

 

 

 

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