• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
The high speed GMLAN serial data circuits are high speed serial data buses used to communicate information between the control modules. Typical data transmission speeds must be high enough to ensure that a required real-time response is maintained. The high speed GMLAN serial data circuits also connect directly to the data link connector (DLC).
• | Supply voltage to the modules are in the normal operating range. |
• | The vehicle power mode requires serial data communications. |
The module setting the DTC has attempted to establish communications on the GMLAN circuits more than 3 times.
• | The module suspends all message transmission. |
• | The module uses default values for all parameters received on the serial data circuits. |
• | The module inhibits the setting of all other communication DTCs. |
• | A current DTC clears when the malfunction is no longer present. |
• | A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction. |
• | An intermittent condition is likely to be caused by a short on the high speed GMLAN serial data circuits. |
• | This DTC cannot be retrieved with a current status. Diagnosis is accomplished using the symptom Scan Tool Does Not Communicate with High Speed GMLAN Device . |
• | Refer to Data Link References for the specific modules using high speed GMLAN serial data. |
Data Link Communications Description and Operation
Control Module References for scan tool information.