GM Service Manual Online
For 1990-2009 cars only

Circuit Description

When an ignition key is inserted into the ignition lock cylinder and switched to ON, the transponder embedded in the head of the key is energized by the exciter coils surrounding the ignition lock cylinder. The energized transponder transmits a signal that contains its unique value, which is received by the body control module (BCM). The BCM then compares this value to a value stored in memory, learned key code. If the value is correct the BCM sends the fuel enable password via the serial data circuit to the powertrain control module (PCM).

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2960 Security System Sensor Data Incorrect But Valid

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

If the transponder value from the ignition key does not match the one stored in memory, the BCM sets this DTC. This DTC indicates the use of a key with a transponder value that has not been learned by the BCM. The vehicle theft deterrent (VTD) system considers this to be a theft attempt.

Action Taken When the DTC Sets

    • The vehicle will not start.
    • The BCM sends a fuel disable message to the PCM via the serial data circuit.
    • The driver information center (DIC) displays Starting Disabled Due To Theft message.

Conditions for Clearing the MIL/DTC

    • The BCM clears the current status of the DTC when it senses a valid key transponder value from the ignition key.
    • The BCM clears the history status of the DTC after 100 fault free ignition cycles.
    • The DTC can be cleared by using a scan tool.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Verifies the condition for setting DTC B2960 is current.

  2. The only method to determine which re-learn procedure to perform.

  3. To set this code, a key with a working transponder that is not learned was read by the BCM. For that key to operate the vehicle and one or more learned keys are available, perform the Adding Keys procedure.

  4. To set this code, a key with a working transponder that is not learned was read by the BCM. For that key to operate the vehicle and there is only one key available, a 10-Minute Relearn Procedure or 30-Minute Relearn Procedure must be performed.

Step

Action

Yes

No

Schematic Reference: Theft Deterrent System Schematics

Connector End View Reference: Theft Deterrent System Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Is DTC B2960 set as a current code?

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

3

Are more than one of the vehicle keys available?

Go to Step 4

Go to Step 6

4

Attempt to start the vehicle using all of the vehicle available master keys.

Do any of the available master keys start the vehicle?

Go to Step 5

Go to Step 6

5

With a learned master key perform the Adding Keys procedure on the suspect key. Refer to Adding Keys .

Is the procedure complete?

Go to Step 7

--

6

Important: If a 10-Minute or 30-Minute Relearn Procedure is performed, all keys not learned at that time will be erased and will not be recognized. Perform the Adding Keys procedure on all keys or instruct the customer how to perform the Adding Keys procedure. Refer to Adding Keys .

Perform the Programming Theft Deterrent System Components procedure. Refer to Programming Theft Deterrent System Components .

Is the procedure complete?

Go to Step 7

--

7

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK