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Hummer H2. Manual - part 1586

connector.

3. Test the TAC module ignition feed circuit

for a short to battery voltage. Refer to
Circuit Testing and Wiring Repairs in
Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 23

1. Turn ON the ignition.

2. Test both TAC motor circuits 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 28

Go to Step 24

Test for poor connections at the TAC module
harness connector. Refer to Testing for
Intermittent Conditions and Poor Connections
and Repairing Connector Terminals in Wiring
Systems.
Did you find and correct the condition?

Go to Step 28

Go to Step 26

Test for poor connections at the PCM harness
connector. Refer to Testing for Intermittent
Conditions and Poor Connections and
Repairing Connector Terminals in Wiring
Systems.
Did you find and correct the condition?

Go to Step 28

Go to Step 27

Replace the TAC module. Refer to Throttle
Actuator Control (TAC) Module Replacement .
Did you complete the replacement?

Go to Step 28

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

Go to Step 28

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 29

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 P0507 (TAC) To DTC U0107) - 4.8L, 5.3L, and 6.0L -

Hummer H2

2004 ENGINE PERFORMANCE

Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2

ENGINE CONTROLS (TROUBLESHOOTING)

SYMPTOMS - ENGINE CONTROLS

Important Preliminary Inspections Before Starting

Perform Diagnostic System Check - Engine Controls before using the symptom tables, and verify that all of
the following are true:

The powertrain control module (PCM) and malfunction indicator lamp (MIL) are operating correctly.

There are no DTCs stored.

The scan tool data is within the normal operating range, refer to Scan Tool Data List .

Verify the customer concern and locate the correct symptom in the table of contents. Inspect the items
indicated under that symptom.

Visual/Physical Inspection

Several of the symptom procedures ask for a careful visual and physical inspection. This step is extremely
important. The visual and physical inspection can lead to correcting a problem without further inspections, and
can save valuable time. Ensure that:

The PCM grounds are clean, tight, and in the proper location.

The vacuum hoses are not split or kinked, and properly connected, as shown on the Vehicle Emission
Control Information label. Inspect thoroughly for any type of leak or restriction.

The mass air flow (MAF) sensor is properly installed. The arrows on the plastic portion of the sensor
must point toward the engine.

The air intake ducts are not collapsed or damaged.

There are no leaks at the throttle body mounting area, the MAF sensor, or the intake manifold sealing
surfaces.

The ignition wires are not cracked, brittle, or carbon tracked.

The engine harness wiring and terminals are properly connected and are not pinched or cut.

Intermittent

IMPORTANT: Inspect for improper installation of electrical components if an intermittent

condition exists. Inspect for aftermarket theft deterrent devices, lights, and
cellular phones. Verify that no aftermarket equipment is connected to the class
2 circuit. If you can not locate an intermittent condition, a cellular phone
communication signal may cause the condition.

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2

Faulty electrical connections or wiring cause most intermittent problems. Perform a careful visual and physical
inspection of the suspect connectors for the following conditions:

Improperly mated connector halves

Terminals that are not seated

Terminals that are damaged or improperly formed

Reform or replace connector terminals in the problem circuit in order to ensure proper contact tension. Refer to
Connector Repairs in Wiring Systems. Remove the terminal from the connector body in order to inspect for
poor terminal wire connection. Refer to Testing for Intermittent Conditions and Poor Connections in
Wiring Systems.

Road test the vehicle with the DMM connected to the suspected circuit. An abnormal reading that occurs when
the malfunction occurs is a good indication that there is a malfunction in the circuit being monitored.

Use a scan tool in order to help detect intermittent conditions. Useful features of the GM Techline scan tool
include the following:

Trigger the Snapshot feature in order to capture and store engine parameters when the malfunction
occurs. Review this stored information in order to see the specific running conditions that caused the
malfunction.

Freeze Frame/Failure Records can also aid in locating an intermittent condition. Review and capture the
information in the Freeze Frame/Failure Record associated with the intermittent DTC being diagnosed.
Drive the vehicle within the conditions that were present when the DTC originally set.

Use the Plot Function on the scan tool in order to plot selected data parameters. Review this stored
information to aid in locating an intermittent problem. Refer to the scan tool Users Guide for more
information.

Any of the following may cause an intermittent malfunction indicator lamp (MIL) with no stored DTC:

The ignition coils are shorted to a ground or arcing at the ignition wires or the spark plugs.

The PCM grounds are loose or dirty. Refer to Engine Controls Schematics .

The ignition control (IC) wires are routed too close to the secondary ignition wires, coils, or the generator.
Ensure that all of the circuits from the PCM to the ignition coils have good connections.

There is an open diode across the A/C compressor clutch or any other open diodes.

Use the following tables when diagnosing a symptom complaint:

IMPORTANT: The problem may or may not turn ON the malfunction indicator lamp (MIL) or

store a DTC.

IMPORTANT: If the intermittent condition exists as a start and then stall, test for DTCs

relating to the vehicle theft deterrent system. Test for improper installation of
electrical options such as lights, cellular phones, etc.

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2

Intermittent Conditions

Hard Start

Surges/Chuggles

Lack of Power, Sluggishness, or Sponginess

Detonation/Spark Knock

Hesitation, Sag, Stumble

Cuts Out, Misses

Poor Fuel Economy

Poor Fuel Fill Quality

Rough, Unstable, or Incorrect Idle and Stalling

Dieseling, Run-On

Backfire

INTERMITTENT CONDITIONS

Intermittent Conditions

Inspection/Test

Action

DEFINITION: The problem is not currently present but is indicated in DTC History.
OR
There is a customer complaint, but the symptom can not currently be duplicated, if the problem is not
DTC related.
Preliminary

Refer to Symptoms - Engine Controls before starting.

Harness/Connector

Many intermittent open or shorted circuits are affected by harness/connector
movement that is caused by vibration, engine torque, bumps/rough pavement, etc.
Test for this type of condition by performing the applicable procedure from the
following list:

Move related connectors and wiring while monitoring the appropriate scan
tool data.

Move related connectors and wiring with the component commanded ON,
and OFF, with the scan tool. Observe the component operation.

With the engine running, move related connectors and wiring while
monitoring engine operation.

If harness or connector movement affects the data displayed, component/system
operation, or engine operation, inspect and repair the harness/connections as
necessary.
Refer to Electrical Connections or Wiring.

Electrical
Connections or
Wiring

Poor electrical connections, terminal tension or wiring problems cause most
intermittents. Refer to Testing for Intermittent Conditions and Poor
Connections , Circuit Testing , Connector Repairs , or Wiring Repairs in

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2

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