DTC B1558 BCM EPROM Checksum Error for Cadillac Catera 1999

DTC B1558 is an internal body control module (BCM) fault.

The checksum is tested once on wake-up. The fault is set if the running checksum does not match the computed checksum.

Stores a DTC B1558 in the BCM memory.

•	The conditions for the fault are no longer present.

•	The use of a scan tool.

•	A history DTC will clear after 50 consecutive ignition cycles if the condition for the fault is no longer present.

Perform the following steps:

Use a scan tool to clear the DTC.
Cycle the ignition switch.
If DTC B1558 is still current, replace the BCM. Refer to Body Control Module Replacement .