GM Service Manual Online
For 1990-2009 cars only

Circuit Description

At the beginning of the ignition cycle, the cellular telephone module performs a test in order to determine if the EEPROM is corrupted. The module performs the test by adding the checksum of the EEPROM block and that block's 2 complement.

Conditions for Setting the DTC

The value of the addition does not equal zero.

Action Taken When the DTC Sets

The cellular telephone module performs the following functions:

    • Clears all of the DTCs
    • Logs DTC B1658 as current
    • Defaults to the following values:
       - Personalization--Factory default
       - Ignition Cycle Counter--0
       - Theft Alarm Condition--Cleared

Diagnostic Aids

If DTC B1658 is set, perform the following steps:

  1. Clear the DTCs.
  2. Cycle the ignition.

If DTC B1658 is still current, replace the cellular telephone module. Refer to one of the following procedures:

    •  Cellular Telephone Replacement
    •  Cellular Telephone Replacement
    •  Cellular Telephone Replacement