U0001

DTC U0001

Circuit Description

Modules connected to the GMLAN serial data circuit monitor for serial data communications on the GMLAN network during normal vehicle operation. Operating information and commands are exchanged among the modules. Each module on GMLAN network maintains a transmit error counter (TEC) and a receive error counter (REC). The counter values increase with detected errors and will decrease with error-free messages. If the TEC value exceeds 255 the controller removes itself from the network and a DTC U0001 will be set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC U0001 High Speed CAN Communication Bus

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to Symptoms - Vehicle. Symptoms - Vehicle






Conditions for Running the DTCs

* Voltage supplied to the module is in the normal operating voltage range.
* The vehicle power mode requires serial data communication to occur.

Conditions for Setting the DTC

A certain number of no valid transmitted messages on the GMLAN serial data circuits are detected by the module.

Action Taken When the DTCs Sets

* The module suspends all message transmission.
* The module uses default values for all parameters received on the GMLAN serial data circuits.
* The module inhibits the setting of all other GMLAN communication DTCs.

Conditions for Clearing the DTC

* 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, without a repeat of the malfunction.

Diagnostic Aids

* This DTC cannot be retrieved with a current status. Diagnosis of current DTC is accomplished via the symptom, Scan Tool Does Not Communicate with GMLAN Device. Refer to Scan Tool Does Not Communicate with High Speed GMLAN Device. Scan Tool Does Not Communicate with High Speed GMLAN Device
* An intermittent condition is likely to be caused by a short on the GMLAN serial data circuits. Use the Scan Tool Does Not Communicate with GMLAN Device procedure in order to isolate an intermittent condition. Refer to Scan Tool Does Not Communicate with High Speed GMLAN Device. Scan Tool Does Not Communicate with High Speed GMLAN Device