Circuit Description
The module contains a data storage area which can save pertinent data when the ignition is turned OFF. The Keep Alive Memory (KAM) data is lost if battery power is removed from the module. The KAM area is an integral part of the microprocessor and cannot be serviced separately.
Conditions for Running the DTC
The module microprocessor must be active/awake.
Conditions for Setting the DTC
DTC B1004 indicates that the keep alive, or long term, memory in the module has been reset. This is a normal occurrence whenever power or ground is removed from the module, such as when the battery is disconnected and reconnected.
Action Taken When the DTC Sets
The microprocessor reverts back to the base programmed critical operating data until new data is learned and stored in KAM.
Conditions for Clearing the MIL/DTC
The DTC will clear when the microprocessor calculates a successful comparison of the periodic check sum to the running check sum.
Diagnostic Aids
| • | This DTC may be stored as a history DTC with out affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the module. |
| • | This DTC will never set as current during testing unless there is a non-recoverable memory failure. |
| • | Intermittent interruptions to either the battery positive voltage (B+) circuit or the module ground circuit will cause the DTC to set. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
| • | If this DTC is retrieved as both a current and history DTC, replace the module. |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check? | -- | Go to Step 2 | |
2 | Replace the module. Refer to OnStar Vehicle Interface Unit Replacement . Did you complete the replacement? | -- | System OK | -- |
