Hummer H2. Manual — part 1637

4

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 O2A fuse.
Is the O2A 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

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.

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

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:

z

HO2S heater low control circuit

z

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

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

-

2004 Hummer H2

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

Hummer H2

DTC P0136 OR P0156

Circuit Description

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the
oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach
operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the
time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the
HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in
open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and closed loop is
achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias
voltage. High HO2S voltage indicates a rich exhaust stream; low HO2S voltage indicates a lean exhaust stream.

The HO2S bank 1 sensor 2 and HO2S bank 2 sensor 2 are used for catalyst monitoring. This diagnostic runs
once per ignition cycle. This diagnostic consists of two tests, a passive test and an intrusive test. During the

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 1 or Heated Oxygen Sensor (HO2S)
Replacement Bank 2 Sensor 1 .
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 P0134 or
P0154?

-

Go to Step 17 in

DTC P0134 or

P0154

Go to Step 23

23

1. Replace the O2A 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

passive test, if the HO2S bank 1 sensor 2 or HO2S bank 2 sensor 2 voltage transitions below 350 mV and above
709 mV, the DTC will pass for this ignition cycle. If the DTC does not pass during the passive test, the intrusive
test will begin. During the intrusive test, the control module will force the air-to-fuel ratio rich and/or lean. The
control module then waits for a predicted response from the HO2S. If the HO2S voltage transitions below 350
mV and/or above 709 mV, the DTC will pass for this ignition cycle. If the control module does not receive the
expected response from the HO2S, DTC P0136 will set for HO2S bank 1 sensor 2 or DTC P0156 will set for
HO2S bank 2 sensor 2.

Conditions for Running the DTC

DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0125, P0131, P0132,
P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0151, P0152, P0153, P0154, P0155, P0157, P0158,
P0160, P0161, P0200, P0442, P0443, P0446, P0449, P0455, P0496, P1133, P1134, P1153, P1154 are not set.

Passive Test

z

The engine is running.

z

The Engine Run Time parameter is less than 13.5 minutes.

Intrusive Test

z

The Engine Run Time parameter is more than 13.5 minutes.

z

The Ignition 1 Signal parameter is between 10-18 volts.

z

The Engine Speed parameter is between 900-5,000 RPM.

z

The MAF Sensor parameter is between 5-55 g/s.

z

The Vehicle Speed parameter is between 24-131 km/h (15-82 mph).

z

The Short Term FT Bank 1 and Bank 2 parameter is between -10 and +10 percent.

z

The maximum number of intrusive attempts is less than 13.

Conditions for Setting the DTC

1. The PCM detects that the HO2S bank 1 sensor 2 or HO2S bank 2 sensor 2 did not transition below 350

mV and above 709 mV during the passive test.

2. One of the following tests fail:

z

Lean Intrusive Test

„

The PCM detects that the HO2S bank 1 sensor 2 or HO2S bank 2 sensor 2 is more than 350
mV for 25.4 seconds.

„

The HO2S bank 1 sensor 1 and HO2S bank 2 sensor 1 is less than 300 mV.

OR

z

Rich Intrusive Test

„

The PCM detects that the HO2S bank 1 sensor 2 or HO2S bank 2 sensor 2 is less than 709
mV for 25.4 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