Hummer H2. Manual - part 1536

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

shorted to a voltage source.

Go to Step 17

Go to Step 14

Measure the voltage from the low signal circuit of
the HO2S harness connector on the engine harness
side to a good ground with a DMM. Refer to Circuit
Testing in Wiring Systems.
Is the voltage more than the specified value?

2 V

Go to Step 12

Go to Step 10

Test the HO2S high signal 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 17

Go to Step 14

1. Connect a 3-amp fused jumper wire between

the high signal circuit of the HO2S harness
connector on the engine harness side and the
low signal circuit of the HO2S harness
connector on the engine harness side.

2. Observe the HO2S voltage parameter with a

scan tool.

Is the HO2S voltage parameter less than the
specified value?

100
mV

Go to Step 13

Go to Step 11

Test the HO2S low signal 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 17

Go to Step 14

Test the HO2S low signal 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 17

Go to Step 14

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 17

Go to Step 15

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 17

Go to Step 16

Replace the affected HO2S. Refer to Heated
Oxygen Sensor (HO2S) Replacement Bank 1

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 P0135 OR P0155

Circuit Description

The heated oxygen sensor (HO2S) must reach operating temperature to provide an accurate voltage signal. A
heating element inside the HO2S minimizes the time required for the sensor to reach operating temperature.
Voltage is provided to the heater by the ignition 1 voltage circuit through a fuse. With the engine running,
ground is provided to the heater by the HO2S heater low control circuit, through a low side driver within the
powertrain control module (PCM). The PCM commands the heater ON or OFF to maintain a specific HO2S
operating temperature range. The PCM determines the temperature by measuring the current flow through the
heater. When the heater is in the ON state, the PCM will pulse the heater OFF for a duration of 50 ms, once per
second. When the heater is in the OFF state, the PCM will pulse the heater ON for a duration of 50 ms, once per
second. The PCM monitors the heater current with the engine running. The PCM also calculates the heater
resistance on a cold start. Both diagnostics will only run once per ignition cycle. If the PCM detects that the
heater current or the heater calculated resistance is not within an expected range, DTC P0135 sets for HO2S
bank 1 sensor 1 or DTC P0155 sets for HO2S bank 2 sensor 1.

Conditions for Running the DTC

Heater Current Test

DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120,
P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101,
P2108, P2135, U0107 are not set.

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

Go to Step 17

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

Go to Step 17

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 18

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

The ECT Sensor parameter is more than 50°C (122°F).

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

The MAF Sensor parameter is between 3-40 g/s.

The Engine Speed parameter is between 500-3,000 RPM.

The Engine Run Time parameter is more than 120 seconds.

Heater Resistance Test

The ignition is OFF for more than 10 hours.

The ECT Sensor parameter is between -30 to +45°C (-22 to +113°F) at engine start-up.

The ECT Sensor parameter minus the IAT Sensor parameter is less than 8°C (14°F) at engine start-up.

The engine is running.

Conditions for Setting the DTC

Heater Current Test

The PCM detects that the affected HO2S heater current parameter is more than 3.125 amps or less than
0.25 amps.

The above condition is met for 10 seconds.

Heater Resistance Test

The PCM detects that the affected HO2S heater calculated resistance is not within an expected range at engine
start-up.

Action Taken When the DTC Sets

The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition
cycle that the diagnostic 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 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

2004 Hummer H2

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

Hummer H2

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.

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 P0135 or P0155

Step

Action

Value

(s)

Yes

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

Did you perform the Diagnostic System Check-
Engine Controls?

Go to Step 2

Go to Diagnostic

System Check -

Engine Controls

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
specified range?

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-

3.125

Go to Step 3

Go to Step 6

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

Go to Step 4

Go to Step 5

1. Operate the vehicle within the Conditions for

Running the Heater Resistance Test.

2004 Hummer H2

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

Hummer H2

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