Hummer H2. Manual - part 1643

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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 consecutive 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.  

Conditions for Clearing the MIL/DTC 

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The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles 
that the diagnostic runs and does not fail.  

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A current DTC, Last Test Failed, clears when the diagnostic runs and passes.  

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A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other 
emission related diagnostic.  

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Clear the MIL and the DTC with a scan tool.  

Test Description 

The number below refers to the step number on the diagnostic table. 

9: With no fault present, the test lamp will blink once per second.  

DTC P0141 or P0161 

Step

Action

Value

(s)

Yes

No

Schematic Reference: Engine Controls Schematics 
Connector End View Reference: Engine Controls Component Views or Powertrain Control 
Module (PCM) Connector End Views

1

Did you perform the Diagnostic System Check-
Engine Controls?

-

Go to Step 2

Go to Diagnostic 

System Check - 

Engine Controls

2

1. Turn ON the ignition, with the engine OFF.  

2. Command the HO2S heaters ON with a scan 

tool.  

3. Wait 15 seconds to allow the HO2S heater 

current to stabilize.  

4. Observe the affected HO2S heater current 

parameter with a scan tool.  

Is the HO2S heater current parameter within the 

IMPORTANT:

Whenever the HO2S heaters are commanded ON 
with a scan tool, they will continue to be pulsed 
ON once per second until the ignition is turned 
OFF for 30 seconds.

0.25-

1.375 

A

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L - 

Hummer H2

  

specified range?

Go to Step 3

Go to Step 6

3

observe the Freeze Frame/Failure Records for this 
DTC. 
Did the DTC fail with an engine run time of less than 
10 seconds?

-

Go to Step 4

Go to Step 5

4

1. Operate the vehicle within the Conditions for 

Running the Heater Resistance Test.  

2. Start the engine.  

Did the DTC fail this ignition?

-

Go to Step 6

Go to Intermittent 

Conditions

5

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 Heater Current Test. 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 6

Go to Intermittent 

Conditions

6

Inspect the O2B fuse. 
Is the O2B fuse open?

-

Go to Step 7

Go to Step 8

7

Test the ignition 1 voltage circuit for a short to 
ground. Refer to Circuit Testing and Wiring 
Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 22

Go to Step 10

8

1. Disconnect the affected HO2S.  

2. Turn ON the ignition, with the engine OFF.  

3. Probe the ignition 1 voltage circuit of the 

HO2S harness connector on the engine harness 
side with a test lamp that is connected to a 
good ground. Refer to Probing Electrical 
Connectors in Wiring Systems.  

Does the test lamp illuminate?

-

Go to Step 9

Go to Step 19

IMPORTANT:

The test lamp may blink prior to commanding the 
heaters ON. This is because the heaters were 
commanded ON in a previous step. To command 
the heaters OFF, turn OFF the ignition for 30 
seconds.

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L - 

Hummer H2

  

9

1. Connect a test lamp between the ignition 1 

voltage circuit of the HO2S harness connector 
on the engine harness side and the HO2S 
heater low control circuit of the HO2S harness 
connector on the engine harness side.  

2. Command the HO2S heaters ON with a scan 

tool.  

Does the test lamp blink once per second?

-

Go to Step 11

Go to Step 12

10

Test the ignition 1 voltage circuit on the sensor side 
of the HO2S connector for a short to ground. Refer 
to Circuit Testing in Wiring Systems.Is any sensor 
shorted to ground?

IMPORTANT:

Perform the following test on all HO2S' which are 
supplied voltage by the suspect circuit.

-

Go to Step 20

Go to Intermittent 

Conditions

11

Measure the resistance of the following circuits with 
a DMM: 

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HO2S heater low control circuit  

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Ignition 1 voltage circuit  

 
Refer to Circuit Testing in Wiring Systems. 
Is the resistance of either circuit more than the 
specified value?

3 ohm

Go to Step 18

Go to Step 16

12 Is the test lamp on steady?

-

Go to Step 13

Go to Step 14

13

Test the HO2S heater low control circuit for a short 
to ground. Refer to Circuit Testing and Wiring 
Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 22

Go to Step 17

14

Test the HO2S heater low control circuit for a short 
to voltage. Refer to Circuit Testing and Wiring 
Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 22

Go to Step 15

15

Test the HO2S heater low control circuit for an open 
or high resistance. Refer to Circuit Testing and 
Wiring Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 22

Go to Step 17

16

Test for shorted terminals and for poor connections 
at the HO2S. Refer to Testing for Intermittent 
Conditions and Poor Connections and Connector 
Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 22

Go to Step 20

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L - 

Hummer H2

  

17

Test for shorted terminals and for poor connections 
at the PCM. Refer to Testing for Intermittent 
Conditions and Poor Connections and Connector 
Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 22

Go to Step 21

18

Repair the circuit with high resistance. Refer to 
Wiring Repairs in Wiring Systems. 
Did you complete the repair?

-

Go to Step 22

-

19

Repair the open or high resistance in the ignition 1 
voltage circuit. Refer to Wiring Repairs in Wiring 
Systems. 
Did you complete the repair?

-

Go to Step 22

-

20

Replace the affected HO2S. Refer to Heated 
Oxygen Sensor (HO2S) Replacement Bank 1 
Sensor 2 or Heated Oxygen Sensor (HO2S) 
Replacement Bank 2 Sensor 2 . 
Did you complete the replacement?

-

Go to Step 22

-

21

Replace the PCM. Refer to Powertrain Control 
Module (PCM) Replacement . 
Did you complete the replacement?

-

Go to Step 22

-

22

Were you sent to this diagnostic from DTC P0140 or 
P0160?

-

Go to Step 17 in 

DTC P0140 or 

P0160

Go to Step 23

23

1. Replace the O2B fuse if necessary.  

2. Clear the DTCs with a scan tool.  

3. Turn OFF the ignition for 30 seconds.  

4. Start the engine.  

5. 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 24

24

Observe the Capture Info with a scan tool. 
Are there any DTCs that have not been diagnosed?

-

Go to 

Diagnostic 

Trouble Code 

(DTC) List

System OK

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L - 

Hummer H2