GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Regal 🢒 Body and Accessories 🢒 Body Control System 🢒 DTC U1300 Class 2 Short to Ground

Object Number: 385137 Size: MF

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 Engine Controls for additional information on PCM related DTCs.

Test Description

The number below refers to the step number on the diagnostic table.

  1. This step determines whether the malfunction is intermittent or the BCM is faulty.

Step

Action

Value(s)

Yes

No

1

Was the Data Link Connector system check performed?

--

Go to Step 2

Go to Data Link Communications System Check in Wiring Systems

2

Was the BCM diagnostic system check performed?

--

Go to Step 3

Go to Diagnostic System Check - Body Control System

3

  1. Turn the ignition switch on.
  2. Clear BCM DTCs. Refer to Clearing DTCs for more information.
  3. Check for BCM current DTCs. Refer to Diagnostic Trouble Code (DTC) Displaying for more information.

Does this BCM DTC reset?

--

Go to Step 4

Go to Step 5

4
  1. Replace the BCM. Refer to Body Control Module Replacement for more information.
  2. After replacing the BCM, perform the Setup New BCM procedure. Refer to Body Control Module (BCM) Programming/RPO Configuration for more information.

Is the repair complete?

--

Go to Step 6

--

5

The malfunction is not present at this time. Refer to Diagnostic Aids for additional information regarding this DTC.

Is the repair complete?

--

Go to Step 6

--

6
  1. Turn the ignition switch off.
  2. Reinstall connectors/components removed.
  3. Turn the ignition switch on.
  4. Clear BCM DTCs. Refer to Clearing DTCs for more information.
  5. Check for BCM current DTCs. Refer to Diagnostic Trouble Code (DTC) Displaying for more information.

Are there any BCM current DTCs set?

--

Go to Diagnostic System Check - Body Control System

System OK