Body Control System Diagnosis

DTC U1300 Class 2 Short To Ground:

CIRCUIT DESCRIPTION
The BCM interfaces with other vehicles Systems through the Class 2 serial data link.

CONDITIONS FOR SETTING THE DTC
The BCM detects a short to ground in the Class 2 serial data link.

ACTION TAKEN WHEN THE DTC SETS
^ The SERVICE VEHICLE SOON indicator lamp turns on.
^ The BCM stores DTC U1300 in memory as a history DTC.

CONDITIONS FOR CLEARING THE DTC
^ The BCM no longer detects a short to ground in the Class 2 serial data link.
^ The BCM monitors its own transmitted message on the Class 2 serial data link.
^ A history DTC will clear after 100 consecutive ignition cycles if the condition for the fault is no longer present.
^ Using a scan tool.

DIAGNOSTIC AIDS
^ DTC U1300 indicates that the Class 2 serial data link has been shorted to ground. The BCM sends DTC information to a scan tool via the Class 2 serial data link. If the Class 2 serial data link is currently shorted to ground, the scan tool will be unable to communicate with the BCM.
Therefore, you will be unable to obtain a DTC U1300 as a current DTC. However, if the scan tool is able to communicate with the BCM and DTC U1300 is read, it will be a history DTC. Wiggle wires and connectors when performing circuit checks on the Class 2 serial data link. This can often cause the short to ground to reappear.
^ The following conditions may cause an intermittent malfunction to occur:
- An intermittent short to ground in the Class 2 serial data link.
- The BCM is shorted to ground internally.
^ DTC P1626 will set in the Powertrain Control Module (PCM) when the ignition switch is on with the Body Control Module (BCM) disconnected. When BCM diagnostics and repairs are completed, refer to Computers and Control Systems for additional information on PCM related DTCs. Computers and Control Systems

TEST DESCRIPTION
The number below refers to the step number on the diagnostic table.
3. This step determines whether the malfunction is intermittent or the BCM is faulty.