Content .. 1695 1696 1697 1698 ..
Chevrolet Silverado / GMC Sierra. Manual - part 1697
Electrical Information Reference
Circuit Testing
Connector Repairs
Testing for Intermittent Conditions and Poor Connections
Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Engine running, observe the GEN-F Terminal Signal parameter in the ECM data list. The
parameter should read between 5 and 95 percent.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the generator.
2. Ignition ON, engine OFF, connect a test lamp to B+ and repeatedly probe the generator
field duty cycle circuit terminal 2, while monitoring the GEN-F Terminal Signal Parameter.
The parameter should change from 0 percent to above 95 percent.
If the parameter was not affected by the test lamp, test the circuit for a short to voltage,
short to ground, or an open/high resistance. If the circuit tests normal, replace the
ECM.
3. If the circuit tests normal, test or replace the generator.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Generator Replacement (4.3L) or Generator Replacement (4.8L, 5.3L, 6.0L, and
6.2L) or Generator Replacement (6.6L)
Control Module References for ECM replacement, setup, and programming
SYMPTOMS - ENGINE ELECTRICAL
IMPORTANT: The following steps must be completed before using the symptom
tables.
2008 Chevrolet Silverado 1500
2008 ENGINE Engine Electrical - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Perform Diagnostic System Check - Vehicle before using the Symptom Tables in order to
verify that all of the following are true:
There are no DTCs set.
The control modules can communicate via the serial data link.
Review the system descriptions and operations in order to familiarize yourself with the
system functions. Refer to one of the following system operations:
Battery Description and Operation
Charging System Description and Operation
Electrical Power Management Description and Operation
Starting System Description and Operation
Visual/Physical Inspection
Inspect for aftermarket devices which could affect the operation of the starting and charging
systems. Refer to Checking Aftermarket Accessories .
Inspect the easily accessible or visible system components for obvious damage or conditions
which could cause the symptom.
Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to
Testing for Intermittent Conditions and Poor Connections .
Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the
symptom:
Battery Inspection/Test
Battery Electrical Drain/Parasitic Load Test
Battery Common Causes of Malfunction
Charging System Test
Generator Noise Diagnosis
Starter Solenoid Does Not Click
Starter Solenoid Clicks, Engine Does Not Crank
Engine Cranks Slowly
Starter Motor Noise Diagnosis
2008 Chevrolet Silverado 1500
2008 ENGINE Engine Electrical - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
BATTERY INSPECTION/TEST
Special Tools
J 42000 Battery Tester. See Special Tools.
Diagnostic Aids
Follow these instructions in order to avoid an incorrect diagnosis because of connections:
If testing the vehicle with the battery cables still connected, wiggle the J 42000 clips on the
terminal bolt. See Special Tools. This may cut through any coating or through any
oxidation that may be present on the bolt.
Even new bolts contain a protective coating that may insulate or cause a resistance in the
test circuit.
If correct connections to the battery terminal bolts in the vehicle are in doubt, perform the
following steps:
1. Disconnect the negative battery cable.
2. Disconnect the positive battery cable.
3. Install the test adapters on the terminals.
4. Follow the instructions for testing a removed battery.
If the tester displays a REPLACE BATTERY or BAD CELL-REPLACE result for a
battery tested in the vehicle with the battery cables connected, perform the following steps:
1. Disconnect the negative battery cable.
2. Disconnect the positive battery cable.
3. Install the tester adapters.
CAUTION: Refer to Battery Disconnect Caution .
IMPORTANT:
The battery test using the J 42000 Battery Tester requires
correct connections to the battery terminals. See Special
Tools. A failure to obtain the correct connections during the
test may result in a failed test on a good battery.
Use the Out of Vehicle test for each battery when testing a
vehicle with dual batteries.
2008 Chevrolet Silverado 1500
2008 ENGINE Engine Electrical - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
4. Follow the instructions for testing a removed battery.
5. Replace the battery only if the second test shows a REPLACE BATTERY or BAD
CELL-REPLACE result.
Use the test code from the second test for any warranty purposes.
Use the correct terminal adapters.
Do not use any common bolts or a combination of bolts, of nuts, and of washers as adapters
when testing the battery.
Use the test adapters that are provided with the J 42000 or GM P/N 12303040 terminal
adapters. See Special Tools. If the adapters that are provided with the J 42000 require
replacement, use GM P/N 12303040. See Special Tools. Any other adapter may not
contact the correct areas of the battery terminal, causing a resistance that may result in an
invalid battery test result.
Circuit/System Testing
1. Inspect the battery for a cracked, broken, or damaged case, which may be indicated by
battery acid leakage.
If there is any apparent damage, replace the battery.
IMPORTANT: Always write the test code displayed by the tester on the
repair order for any warranty purposes. The number is a
unique code that describes the test data for a particular
battery at a particular time. The test code may
occasionally repeat when you retest the same battery.
More often, each test will result in a different code. Use
the test code from the second, or Out of Vehicle test.
CAUTION: Unless directed otherwise, the ignition and start switch must
be in the OFF or LOCK position, and all electrical loads must
be OFF before servicing any electrical component. Disconnect
the negative battery cable to prevent an electrical spark
should a tool or equipment come in contact with an exposed
electrical terminal. Failure to follow these precautions may
result in personal injury and/or damage to the vehicle or its
components.
2008 Chevrolet Silverado 1500
2008 ENGINE Engine Electrical - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Content .. 1695 1696 1697 1698 ..