GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2001 🢒 Catera 🢒 DTC 🢒 DTC B2556

Circuit Description

The keyless entry receiver is integrated within the body control module (BCM). The calibrations for the receiver are stored in EEPROM. When the ignition is first turned On, the receiver performs internal tests on the EEPROM and can determine the integrity of the EEPROM's non-volitale memory. The receiver then compares its previously stored checksum with the checksum calculated when the ignition was first turned On. If the two checksums do not match, the receiver indicates that a calibration error (checksum error) has occurred.

Conditions for Setting the DTC
    • The stored checksum does not match the calculated checksum.
    • The receiver detects an internal memory malfunction (checksum error).
    • This condition must occur when the ignition is first turned On.

Action Taken When the DTC Sets
    • Stores a DTC B2556 in the receiver memory.
    • Disables all keyless entry functions.

Conditions for Clearing the DTC
    • 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.
    • This DTC requires an ignition cycle in order to change from a current to history.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. The EEPROM is not removable from the keyless entry receiver and a DTC B2556 is an internal malfunction to the receiver. The repair procedure is to replace the BCM.

Step

Action

Yes

No

1

Did you perform the Keyless Entry Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Remote Keyless Entry

2

  1. Replace the body control module (BCM). Refer to Body Control Module Replacement in Body Control System.
  2. Reprogram the transmitters to the new BCM.

Did you complete the replacement?

System OK

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