Hummer H2. Manual — part 1595

z

The MIL will illuminate with ignition switch ON and the engine not running.

z

The MIL will turn OFF when the engine is started.

z

The MIL will remain ON if the self-diagnostic system has detected a malfunction.

z

The MIL may turn OFF if the malfunction is not present.

z

If the MIL is illuminated and then the engine stalls, the MIL will remain illuminated so long as the
ignition switch is ON.

z

If the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition switch is
cycled OFF, then ON.

Diagnostic Aids

If the problem is intermittent, refer to Intermittent Conditions .

Test Description

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

2: This step determines if the condition is with the MIL control circuit or the PCM.

Malfunction Indicator Lamp (MIL) Always On

Step

Action

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 OFF the ignition.

2. Disconnect the PCM.

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

4. Observe the MIL.

Is the MIL illuminated?

Go to Step 3

Go to Step 5

3

1. Remove the instrument panel cluster (IPC).

Refer to Instrument Panel Cluster (IPC)
Replacement in Instrument Panel, Gauges, and
Console.

2. Test the MIL 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 6

Go to Step 4

Replace the IPC. Refer to Instrument Panel Cluster

2004 Hummer H2

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

ENGINE CRANKS BUT DOES NOT RUN

Description

The Engine Cranks but Does Not Run diagnostic table is an organized approach to identifying a condition that
causes an engine to not start. The diagnostic table directs the service technician to the appropriate system
diagnosis. The diagnostic table assumes the following conditions are met:

z

The battery is completely charged. Refer to Battery Inspection/Test (Non-HP2) in Engine Electrical.

z

The engine cranking speed is acceptable. Refer to Engine Cranks Slowly in Engine Electrical.

z

There is adequate fuel in the fuel tank.

Engine Cranks but Does Not Run

4

(IPC) Replacement in Instrument Panel, Gauges, and
Console.
Did you complete the replacement?

Go to Step 6

-

5

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

Go to Step 6

-

6

1. Turn the ignition OFF for 30 seconds.

2. Start the engine.

3. Observe the MIL.

Does the MIL operate correctly?

Go to Step 7

Go to Step 2

7

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

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End 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

Crank the engine for the specified amount of time.
Does the scan tool display any DTCs that failed this
ignition?

15 seconds

Go to

Diagnostic

Trouble Code

(DTC) List

Go to Step 3

3

Does the scan tool display any body control module
(BCM) vehicle theft deterrent (VTD) DTCs?

-

Go to

Diagnostic

System Check -

2004 Hummer H2

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

Theft Deterrent

in Theft

Deterrent

Go to Step 4

4

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

2. Probe both sides of the powertrain control

module (PCM) 1 fuse located in the
underhood electrical center with a test lamp
connected to a good ground.

Does the test lamp illuminate on at least one side of
the fuse?

-

Go to Step 5

Go to Ignition

Relay

Diagnosis

5

Monitor the ignition 1 signal parameter with a scan
tool.
Is the ignition 1 signal parameter at the specified
value?

B+

Go to Step 6

Go to Step 10

6

Command the fuel pump ON with a scan tool.
Does the fuel pump operate?

-

Go to Step 7

Go to Fuel

Pump

Electrical

Circuit

Diagnosis

7

1. Turn OFF the ignition.

2. Disconnect a spark plug wire.

3. Install the J 26792 Spark Tester.

4. Attempt to start the engine.

5. Repeat test for remaining cylinders.

Does the spark tester spark for all cylinders?

-

Go to Step 8

Go to

Electronic

Ignition (EI)

System

Diagnosis

8

1. Turn OFF the ignition.

2. Install a fuel pressure gauge. Refer to Fuel

System Diagnosis .

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

4. Observe the fuel pressure while the fuel

pump is operating.

Is the fuel pressure within the specified range?

IMPORTANT:

The fuel pump operates for about 2
seconds when the ignition is turned ON.
The fuel pressure must be observed when
the fuel pump is operating.

VIN V, T, U

Gasoline:

385-425 kPa

(55-62 psi)

VIN Z

Ethanol:

335-375 kPa

(48-54 psi)

Go to Step 9

Go to Fuel

System

Diagnosis

Inspect for the following conditions:

2004 Hummer H2

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

9

z

The engine coolant temperature (ECT) sensor
is not close to the actual engine temperature.
Refer to DTC P0125 .

z

The duct work between the mass air flow
(MAF) sensor and the throttle body for air
leaks

z

A restricted exhaust system-Refer to
Restricted Exhaust in Engine Exhaust.

z

A malfunctioning MAF sensor may cause a
no start or a stall after a start. If you suspect
this, disconnect the MAF sensor. The PCM
will default to the speed density in order to
calculate the engine load and the intake air
flow. If disconnecting the MAF sensor
corrects the condition and the connections are
OK. Refer to DTC P0102 .

z

The spark plugs for being gas fouled-Refer to
Spark Plug Inspection .

z

An engine mechanical failure that causes an
engine not to start such as timing chain, low
compression-Refer to Engine Compression
Test and Symptoms - Engine Mechanical in
Engine Mechanical - 4.8L, 5.3L, and 6.0L.

z

Compare the MAP/BARO parameters to
another vehicle. The parameter values should
be close to each other.

Did you complete the action?

-

Go to Step 13

-

10

1. Test the ignition 1 voltage circuits that are

supplied by the PCM 1 fuse for an open or
for a short to ground. Refer to Circuit
Testing and Wiring Repairs in Wiring
Systems.

2. Replace the fuse if necessary.

Did you find and correct the condition?

-

Go to Step 13

Go to Step 11

11

Inspect for poor connections at the harness
connector of 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 13

Go to Step 12

12

Replace the PCM. Refer to Powertrain Control
Module (PCM) Replacement .

-

2004 Hummer H2

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