Hummer H1 (2006+). Manual - part 56

 

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Hummer H1 (2006+). Manual - part 56

 

 

OBD-68

On-Board Diagnostics

_______________________________________________

Diagnostic Aids 

• There are no driveability concerns associated with the FRP regulator unless a DTC is present. The most likely cause of this 

DTC is a sticking FRP regulator. 

• If the fuel system pressure is actually too high, a fuel knock and smoke condition will exist. 

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” performed?

Go to step 2.

Go to OBD 

System

Check.

    2

1.

Turn ON the ignition, with the engine OFF.

2.

Observe the Actual Fuel Rail Pressure parameter with a scan tool.

Is the Actual Fuel Rail Pressure parameter within the specified range?

1.1-1.4

MPa

Go to Step 3

Go to Step 6 

    3

Did DTC P0090 also set?

Go to the 

Diagnostic

for P0090 

before diag-

nosing this 

code

Go to Step 4 

    4

Did DTC P1093 also set?

Go to the 

Diagnostic

for P1093 

before diag-

nosing this 

code

Go to Step 5

    5

1.

Start and run the engine at 2,000 RPM.

2.

Observe the Actual Fuel Rail Pressure parameter and the Desired 
Fuel Rail Pressure parameter with a scan tool.

Does the scan tool display a pressure difference more than the speci-
fied value?

167 MPa

Go to Step 11 

Go to Step 6

    6

1.

Start and idle the engine.

2.

Perform the following test at idle and at 2,000 RPM:

• Change the fuel pressure with a scan tool, incrementing through 

the entire fuel pressure range. 

• Observe the actual vs desired fuel pressures at each fuel pres-

sure level. 

Does the fuel pressure increment and stabilize through the entire fuel
pressure range, with actual and desired fuel pressure within 2 MPa of
each other at every fuel pressure?

Go to Diag-

nostic Aids

Go to Step 11

    7

1.

Disconnect the fuel rail pressure (FRP) sensor.

2.

Observe the Actual Fuel Rail Pressure parameter with a scan tool.

Does the Actual Fuel Rail Pressure measure more than the specified
value?

175 MPa

Go to Step 10 

Go to Step 8

    8

Test the FRP sensor signal circuit 509 (YL) for a short to ground. 

Did you find and correct the condition?

Go to Step 12

Go to Step 9

______________________________________________

 On-Board Diagnostics  OBD-69

5745804

    9

Replace the faulty engine control module (ECM). 

Did you complete the replacement?

Go to Step 12 

   10

Replace the faulty FRP sensor.

Did you complete the replacement?

Go to Step 12

   11

Replace the FRP regulator. 

Did you complete the replacement?

Go to Step 12 

   12

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 13

   13

1.

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

Go to the 

applicable

DTC table.

System OK.

Step

Action

Value(s)

Yes

No

OBD-70

On-Board Diagnostics

_______________________________________________

DTC P0090 Fuel Rail Pressure Control Circuit (Figure OBD-22)

Figure OBD-22:   Fuel Pressure Regulator and Fuel Pressure Sensor Circuits

Circuit Description

The engine control module (ECM) supplies power and ground to the fuel rail pressure (FRP) regulator. The ECM monitors current
on the circuits to detect a failure. If the current is outside of the expected range, DTC P0090 will set.

Conditions for Setting the DTC

The FRP regulator circuit current is not between 50-1,600 mA.

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. 

______________________________________________

 On-Board Diagnostics  OBD-71

5745804

Diagnostic Aids 

• There are no driveability concerns associated with the FRP regulator unless a DTC is present. The most likely cause of this 

DTC is a sticking FRP regulator. 

• If the fuel system pressure is actually too high, a fuel knock and smoke condition will exist. 

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” performed?

Go to step 2.

Go to OBD 

System

Check.

    2

Is DTC U0105 present also?

Go to DTC 

U0100-

U0299 and 

diagnose first 
in Computer/

Integrating 

Systems

before diag-

nosing this 

code

Go to Step 3 

    3

NOTE: Failure to wait until there is no engine control module (ECM)
communications with the scan tool will result in misdiagnosis.

1.

Turn OFF the ignition for 30 seconds.

2.

Turn ON the ignition, with the engine OFF.

3.

Observe the FRP Regulator Command parameter with a scan tool.

Is the FRP Regulator Command more than the specified value?

20%

Go to Step 4

Go to Step 20

    4

Attempt to start the engine.

Does the engine start?

Go to Step 5 

Go to Step 6

    5

1.

Start the engine.

2.

Observe the Actual Fuel Rail Pressure and the Desired Fuel Rail 
Pressure with a scan tool.

Does the scan tool display a pressure difference more than the speci-
fied value?

5 MPa

Go to Step 7 

Go to Diag-

nostic Aids

    6

1.

Turn OFF the ignition.

2.

Disconnect the engine control module (ECM) connectors.

3.

Disconnect the fuel rail pressure (FRP) regulator connector.

4.

Measure the resistance from the control circuit of the FRP regula-
tor to ground with a DVOM.

Does the resistance measure at the specified value?

Go to Step 17

Go to Step 14

    7

1.

Turn OFF the ignition.

2.

Disconnect the FRP regulator harness connector.

3.

Turn ON the ignition, with the engine OFF.

4.

Probe the supply circuit of the fuel rail pressure regulator with a 
Test Lamp connected to a good ground. 

Does the test lamp illuminate?

Go to Step 8

Go to Step 10

 

 

 

 

 

 

 

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