B0996

DTC B0996

Circuit Description

After a loss of battery power has been restored the theft deterrent control module will perform a check on the stored vehicle identification number (VIN). If the VIN is CORRECT, the remote control door lock receiver (RCDLR) will run the VIN Timer for a programmable length of time, typically 10 minutes. The RCDLR will send a message via the serial data circuit to the instrument panel cluster (IPC) to illuminate the SECURITY indicator. After the VIN Timer has timed out, the security indicator will turn OFF. If the VIN is INCORRECT, the RCDLR will send the fuel disable password to the engine control module (ECM) via the serial data circuit. The vehicle theft deterrent (VTD) system considers this to be a tamper and will not allow the vehicle to start. The RCDLR will send a message via the serial data circuit to the IPC to flash the SECURITY indicator.

Substitution detection is based on 5 correct responses from the following modules:

* IPC
* Rear integration module (RIM)
* Driver door module (DDM)
* Front passenger door module (FPDM)
* Left rear door module (LRDM)
* Right rear door module (RRDM)
* Driver position module (DPM)

The modules compare their VIN to that stored in the VIN master on every ignition ON cycle and report their status to the RCDLR. The RCDLR will only check the modules status to see the 5 correct matches when a battery reconnect has been recognized within the theft deterrent module.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B0996 Vehicle Electronic Control Unit (ECU) VIN Check Error






Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

* The VIN check flag of the theft deterrent control module is true.
* The RCDLR has determined that the battery has been reconnected after a disconnect.

Action Taken When the DTC Sets

* The vehicle will not start.
* The RCDLR sends the fuel disable message via the serial data circuit to the ECM.
* The RCDLR will run the VIN Timer for a programmable length of time, typically 10 minutes.
* The RCDLR sends a message to the IPC to illuminate the SECURITY indicator.

Conditions for Clearing the MIL/DTC

* The RCDLR clears the current DTC when the correct VIN information is present.
* The DTC can be cleared by using a scan tool.

Diagnostic Aids

The VIN information is stored during the Setup New RCDLR procedure on a GM SPO replacement part. When the manufacturers enable counter (MEC) is equal to 0 the VIN information cannot be changed. DTC B0996 will set the when the RCDLR does not receive the required 5 correct VIN responses from the modules which report to the theft deterrent module.

Test Description

Step 1 - Step 6:

The number below refers to the step number on the diagnostic table:
2. The RCDLR compares the stored VIN of 7 modules to that of the dash integration module (DIM). If any 2 of the 7 modules is mismatched to the VIN stored in the DIM, DTC B0996 will set.