Yukon XL 2500 2WD V8-8.1L VIN G (2004)
Information Bus: Symptom Related Diagnostic Procedures
A Symptoms - Data Link Communications
SYMPTOMS
IMPORTANT: The following steps must be completed before using the symptom tables.
1. Perform the applicable diagnostic system check before using the Symptom Tables in order to verify that there are no DTCs set.
2. Review the system operation in order to familiarize yourself with the system functions. Refer to Data Link Communications Description and
Operation.
Visual/Physical Inspection
-
Inspect for aftermarket devices which could affect the operation of the vehicle systems.
-
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.
Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:
-
Scan Tool Does Not Power Up
-
Scan Tool Does Not Communicate with Class 2 Device
Scan Tool Does Not Communicate With Class 2 Device
SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE
CIRCUIT DESCRIPTION
Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information
and commands are exchanged among the modules. Connecting a scan tool to the DLC allows communication with the modules for diagnostic
purposes.
DIAGNOSTIC AIDS
The engine will not start when there is a total loss of class 2 serial data communication while the ignition is OFF. The following conditions will cause
a total loss of class 2 serial data communication:
-
A class 2 serial data circuit shorted to ground.
-
A class 2 serial data circuit shorted to voltage.
-
An internal condition within a module or connector on the class 2 serial data circuit, that causes a short to voltage or ground to the class 2 serial
data circuit.
TEST DESCRIPTION