GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The Passlock module calculates a checksum for the contents of the EEPROM when the voltage is first applied. This calculated checksum is compared with the checksum value stored in the EEPROM.

Conditions for Setting the DTC

The calculated checksum is compared with the checksum value stored in the EEPROM. If the 2 values are not equal, DTC B1007 is set. The Passlock module writes certain information onto the EEPROM. If the Passlock module is unable to write onto the EEPROM, DTC B1007 is set.

Conditions for Clearing the MIL/DTC

  1. A history DTC will clear after 100 consecutive ignition cycles occur without a fault.
  2. Use the Scan Tool in order to clear the history and the current DTCs.

Diagnostic Aids

Most intermittent faults are caused by a faulty electrical connection or the wiring. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems for a detailed explanation of how to locate and repair intermittent conditions.

Test Description

The step number below refers to the step number in the Loss of VCM Class 2 Communications Diagnostic Table.

  1. This test inspects for an intermittent condition.

Step

Action

Yes

No

1

Was the Theft Deterrent System Diagnostic System Check performed?

Go to Step 2

Go to Diagnostic System Check - Theft Deterrent

2

  1. Install a scan tool.
  2. Turn the ignition ON with the engine OFF.
  3. Use a scan tool in order to clear the DTCs.

Does the scan tool indicate that DTC 1007 is current?

Go to Step 3

Go to Diagnostic Aids

3

Replace the VIM Module. Refer to Theft Deterrent Module Replacement .

Did you complete the replacement?

Go to Step 4

--

4

  1. Use a 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