Circuit Description
The DTC B1004 is a condition internal to the vehicle interface unit (VIU). The DTC B1004 may be caused by a momentary loss of battery positive voltage or ground to the VIU.
Conditions for Running the DTC
The Ignition must be in the Run or ACC position and the VIU power must be on. The VIU will run this internal test every 300 msec. The battery voltage must be at least 9.5 volts and no more that 15.5 volts.
Conditions for Setting the DTC
The VIU detects an interruption of battery positive or ground.
Action Taken When the DTC Sets
The B1004 code will probably never be retrieved as current. The VIU is unable to communicate on the Class 2 Serial Data Circuit, thus DTC B1004 will most likely be set only as a history DTC.
Conditions for Clearing the DTC
The code can be cleared when the VIU does not detect a failure during the last diagnostic cycle.
Diagnostic Aids
If B1004 sets intermittently, test that battery positive voltage and ground for poor connections.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the OnStar® Diagnostic System Check? | -- | Go to Step 2 | Go to OnStar System Check |
2 |
Important: Perform the set up procedure for the VIU. Replace the VIU. Refer to OnStar Vehicle Interface Unit Replacement . Did you complete the replacement? | -- | System OK | -- |
