ION L4-2.4L (2007)
Information Bus: Symptom Related Diagnostic Procedures
A Symptoms - Data Communications
Symptoms - Data Communications
Important: The following steps must be completed before using the symptom tables.
1. Perform the 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 links. See: Testing and Inspection/Initial Inspection and Diagnostic
Overview/Diagnostic System Check - Vehicle
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 systems. Refer to Checking Aftermarket Accessories. See: Testing and
Inspection/Component Tests and General Diagnostics
* 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.
See: Testing and Inspection/Component Tests and General Diagnostics
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 High Speed GMLAN Device
* Scan Tool Does Not Communicate with Low Speed GMLAN 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 data link connector (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 serial data bus can not be used to
analyze a malfunction on the class 2 serial data bus. The following conditions will cause a total loss of class 2 serial data communication:
* A class 2 serial data circuit shorted to ground. A history U1300 will set in all modules. Refer to DTC U1300, U1301, or U1305. See: Testing and
Inspection/Diagnostic Trouble Code Tests and Associated Procedures/U Code Charts/U1300 See: Testing and Inspection/Diagnostic Trouble
Code Tests and Associated Procedures/U Code Charts/U1301 See: Testing and Inspection/Diagnostic Trouble Code Tests and Associated
Procedures/U Code Charts/U1305
* A class 2 serial data circuit shorted to voltage. A history U1301 will set in all modules. Refer to DTC U1300, U1301, or U1305. See: Testing and
Inspection/Diagnostic Trouble Code Tests and Associated Procedures/U Code Charts/U1300 See: Testing and Inspection/Diagnostic Trouble
Code Tests and Associated Procedures/U Code Charts/U1301 See: Testing and Inspection/Diagnostic Trouble Code Tests and Associated
Procedures/U Code Charts/U1305
* 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
