GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The theft deterrent control module checks the theft deterrent exciter module supply circuit for a low voltage condition. If a low voltage condition is present DTC B2947 will set.

Conditions for Running the DTC

The theft deterrent control module must see the ignition switch input. The theft deterrent control module can not have DTC B1327 set as a current DTC.

Conditions for Setting the DTC

If the theft deterrent control module senses the supply voltage to the theft deterrent exciter module is 0 V for 1 second.

Action Taken When the DTC Sets

Important: If the theft deterrent control module is unable to measure the ignition key transponder value for 30 consecutive seconds, after the vehicle has started, the theft deterrent control module will enter a fail enable state. The vehicle will not stall or stop running. If the theft deterrent control module is in a fail enable state when the ignition is turned to OFF, it will remain fail enabled until the next time the vehicle is started. If the theft deterrent control module is fail enabled, the VTD system is NOT active and the vehicle will start. The theft deterrent control module WILL send its enable password even if a transponder value is not received. The theft deterrent control module will remain fail enabled until the module measures a valid key transponder value.

    • The theft deterrent control module sends a class 2 message containing a disable password to the powertrain control module (PCM).
    • The vehicle will not start.
    • The theft deterrent control module sends a class 2 message to the instrument cluster to illuminate the SECURITY indicator on steady.

Conditions for Clearing the MIL/DTC

The theft deterrent control module clears the current status of the DTC when it does not sense a 0 V condition on the theft deterrent exciter module supply circuit. The DTC will still be retrieved as current until the ignition switch is cycled. The DTC will become a history DTC at that time.

Diagnostic Aids

Refer to Testing for Intermittent Conditions and Poor Connections and Testing for Electrical Intermittents in Wiring Systems.

Test Description

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

  1. Make sure the good ground used is separate from the grounds used by the theft deterrent control module. Voltage measurement must not interfere with possible isolated module ground.

Step

Action

Value(s)

Yes

No

Schematic Reference: Theft Deterrent System Schematics

Connector End View Reference: Theft Deterrent System Connector End Views

1

Did you perform the Theft Deterrent Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - Theft Deterrent

2

  1. Turn OFF the ignition.
  2. Disconnect the theft deterrent exciter module.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the security system sensor supply voltage circuit to a good ground.

Does the voltage measure near the specified value?

12 V

Go to Step 4

Go to Step 3

3

Test the security system sensor supply voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 8

Go to Step 5

4

Inspect for poor connections at the harness connector of the theft deterrent exciter module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 8

Go to Step 6

5

Inspect for poor connections at the harness connector of the theft deterrent control module harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems .

Did you find and correct the condition?

--

Go to Step 8

Go to Step 7

6

Replace the theft deterrent exciter module. Refer to Theft Deterrent Exciter Module Replacement .

Did you complete the replacement?

--

Go to Step 8

--

7

Important: If a 10 Minute or 30 Minute Re-Learn 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 .

  1. Replace the theft deterrent control module . Refer to Theft Deterrent Module Replacement .
  2. With a scan tool, perform the Set Up New VTD Module procedure in the theft deterrent control module Special Functions data list.
  3. Perform the Programming Theft Deterrent System Components procedure. Refer to Programming Theft Deterrent System Components .

Did you complete the replacement?

--

Go to Step 8

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8

  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