GM Service Manual Online
For 1990-2009 cars only

Schematic

Refer to

Vehicle Theft Deterrent Module (VTD)


Object Number: 404751  Size: FS
Battery Voltage to the Rear Fuse Block
INJ1 and INJ2 Fuses, CR CONT, PCM IGN Fuses (Underhood Fuse Block)
Ignition Switch
G201 (2 of 3)
G201 (2 of 3)
Vehicle Theft Deterrent (VTD) Description
Theft Deterrent System Components
schematic

Circuit Description

The vehicle theft deterrent (VTD) controller module checks the exciter module supply circuit for a constant voltage condition.

Conditions for Running the DTC

The VTD controller module must see the ignition switch input. The VTD can not have a B1327 DTC set as a current DTC.

Conditions for Setting the DTC

The VTD controller module requires 1 second to monitor the ignition key. After the first second, the VTD controller module turns off the power to the exciter module. If the VTD controller module senses the supply to the exciter moduleis 12 V for 1 second, the VTD module sets this DTC.

Action Taken When the DTC Sets

The VTD controller module will "fail enable" the VTD system and allow the vehicle to start. The VTD controller module will illuminate the security indicator.

Conditions for Clearing the DTC

The VTD controller module clears the current status of the DTC when it does not sense a 12 V condition on the 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.

Test Description

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

  1. Be sure that the original ignition key issued with the vehicle is used when performing the Vehicle Theft Deterrent Diagnostic System Check.

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

Step

Action

Value(s)

Yes

No

1

Did you perform A Vehicle Diagnostic System Check - Theft Deterrent ?

--

Go to Step 2

Go to Diagnostic System Check - Theft Deterrent

2

  1. Turn OFF the ignition.
  2. Disconnect the exciter/receiver.
  3. Measure the voltage from the exciter/receiver 12 volt reference circuit to a good ground.

Does the voltage measure near the specified value?

B+

Go to Step 4

Go to Step 3

3

Test the exciter/receiver 12 volt reference circuit for a short to ground. Refer to Circuit Testing in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 8

Go to Step 5

4

Inspect for poor connections/terminal tension at the exciter/receiver 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 6

5

Inspect for poor connections/terminal tension at the vehicle theft deterrent (VTD) 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 VTD receiver/exciter. Refer to Reader/Exciter Replacement

Did you complete the replacement?

--

Go to Step 8

--

7

Important: Perform the vehicle theft deterrent module set up procedure after replacing the module.

Replace the VTD module. Refer to Theft Deterrent Module Replacement .

Did you complete the replacement?

--

Go to Step 8

--

8

Clear the diagnostic trouble codes.

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