Chevrolet Silverado / GMC Sierra. Manual — part 230

The fourth through ninth digits are the last 6 digits of the VIN.

DIAGNOSTIC INFORMATION AND PROCEDURES

DIAGNOSTIC STARTING POINT - ENGINE MECHANICAL

Begin the system diagnosis by reviewing the Disassembled Views, Engine Component
Description, Lubrication Description, and Camshaft Position Actuator and Solenoid
Valve Description. Reviewing the description and operation information helps you determine
the correct symptom diagnostic procedure when a malfunction exists. Reviewing the description
and operation information also helps you determine if the condition described by the customer is
normal operation. Refer to Symptoms - Engine Mechanical in order to identify the correct
procedure for diagnosing the system and where the procedure is located.

SYMPTOMS - ENGINE MECHANICAL

Strategy Based Diagnostics

1. Perform the Diagnostic System Check - Vehicle before using the symptom tables.

2. Review the system operations in order to familiarize yourself with the system functions.

Refer to Disassembled Views, Engine Component Description, Lubrication
Description, and Camshaft Position Actuator and Solenoid Valve Description.

All diagnosis on a vehicle should follow a logical process. Strategy based diagnostics is a uniform
approach for repairing all systems. The diagnostic flow may always be used in order to resolve a
system condition. The diagnostic flow is the place to start when repairs are necessary. For a
detailed explanation, refer to Strategy Based Diagnosis .

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the engine. Refer to
Checking Aftermarket Accessories .

Inspect the easily accessible or visible system components for obvious damage or conditions
which could cause the symptom.

Inspect for the correct oil level, proper oil viscosity, and correct filter application.

Verify the exact operating conditions under which the concern exists. Note factors such as
engine RPM, ambient temperature, engine temperature, amount of engine warm-up time,
and other specifics.

Compare the engine sounds, if applicable, to a known good engine and make sure you are
not trying to correct a normal condition.

2008 Hummer H2

2008 ENGINE Engine Mechanical - 6.2L - H2

Intermittent

Test the vehicle under the same conditions that the customer reported in order to verify the system
is operating properly.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the
symptom:

Base Engine Misfire without Internal Engine Noises

Base Engine Misfire with Abnormal Internal Lower Engine Noises

Base Engine Misfire with Abnormal Valve Train Noise

Base Engine Misfire with Coolant Consumption

Base Engine Misfire with Excessive Oil Consumption

Engine Noise on Start-Up, but Only Lasting a Few Seconds

Upper Engine Noise, Regardless of Engine Speed

Lower Engine Noise, Regardless of Engine Speed

Engine Noise Under Load

Engine Will Not Crank - Crankshaft Will Not Rotate

Coolant in Combustion Chamber

Coolant in Engine Oil

Engine Compression Test

Cylinder Leakage Test

Oil Consumption Diagnosis

Oil Pressure Diagnosis and Testing

Cylinder Deactivation (Active Fuel Management) Oil Pressure Relief Valve
Diagnosis and Testing

Camshaft Position Actuator and Solenoid Valve Diagnosis and Testing

Oil Leak Diagnosis

Crankcase Ventilation System Inspection/Diagnosis

Drive Belt Chirping, Squeal, and Whine Diagnosis

Drive Belt Rumbling and Vibration Diagnosis

Drive Belt Falls Off and Excessive Wear Diagnosis

Drive Belt Tensioner Diagnosis

2008 Hummer H2

2008 ENGINE Engine Mechanical - 6.2L - H2