For 1990-2009 cars

### 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.

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

### Diagnostic Aids

• | The DTC may be set as a history DTC with no affect on the control module.

• | If the DTC is retrieved as both a history DTC and a current DTC, the module must be replaced.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Body Control System Schematics
1 | Perform the Diagnostic System Check for the system exhibiting symptoms. Did you perform the Diagnostic System Check for the system exhibiting symptoms? | Go to Step 2 | Go to Diagnostic System Check for the system exhibiting symptoms
2 | Does the scan tool indicate that the DTC is current? | Go to Step 3 | Go to Diagnostic Aids
3 | Important: Perform the set up procedure for the BCM. Replace the BCM. Refer to Body Control Module Replacement . Did you complete the replacement? | System OK | --