GM Service Manual Online
For 1990-2009 cars only

Circuit Description

DTC B1556 is an internal Body Control Module (BCM) fault.

Conditions for Setting the DTC

The BCM performs a data check on every EEPROM write. The BCM sets this fault if the data does not match after three consecutive attempts.

Action Taken When the DTC Sets

Stores a DTC B1556 in the BCM memory.

Conditions for Clearing the DTC

    • The conditions for the fault are no longer present.
    • The use of the scan tool.
    • A history DTC will clear after 50 consecutive ignition cycles if the condition for the fault is no longer present.

Diagnostic Aids

Perform the following steps if DTC B1556 is set:

  1. Clear the DTC with a scan tool.
  2. Cycle the ignition switch.
  3. If DTC B1556 is still current, replace the BCM.