B556

EEPROM Location:

DESCRIPTION:

EEPROM contains specific vehicle information such as:

Vehicle identification number, accumulated vehicle mileage, certain vehicle options and other pertinent information. Since this information is programmed for the specific vehicle in which it is installed, an EEPROM cannot be exchanged from one vehicle to another. Replacement EEPROMs must be obtained through an authorized Delco Electronics Service Center. Contact the nearest EEPROM Service Center and provide them with to the following information:

1. Complete vehicle identification number. Current vehicle mileage. Optional equipment on vehicle, twilight sentinel (T82)*, voice information system (UV1)*, and Canadian base equipment (Z49)*. Option codes are listed on the service parts identification label located under the rear deck lid.

2. The claim form received with the EEPROM should be completed, one copy attached to the repair order and the remainder returned to the service center along with the faulty EEPROM.

3. Remove I.P. compartment door then detach and move aside the relay center bracket assembly and fuse panel.

4. With ignition "OFF", disconnect BCM harness, loosen BCM to bracket retaining nuts and remove BCM.

5. Remove 4 screws from EEPROM access cover, remove cover and engage one end of the EEPROM carrier with the hook end of the rocker type PROM removal tool. Press on the vertical bar end of the tool and rock the engaged end of the EEPROM carrier up as far as possible. Engage the opposite end of the EEPROM carrier and in the same manner repeat the process until the EEPROM and carrier are free of the socket.

6. Carefully install the new EEPROM, mounted in carrier, into the BCM socket while aligning the small notch in carrier with small notch in socket. Then press on the EEPROM carrier only until the EEPROM is firmly seated in the socket.

7. Reinstall access cover, 4 screws and BCM. (Reverse step numbers 3 and 4.)

8. Enter diagnostics and clear BCM code(s). Start engine and observe the odometer display. If "ERROR" continues to be displayed and the EEPROM is properly installed, replace the BCM.

Code B556 indicates that the EEPROM, which records elapsed odometer mileage, is not being read by the BCM. Usually along with code B556 "ERROR" WILL BE DISPLAYED IN THE ODOMETER DISPLAY. Check for proper EEPROM installation. If PROM is properly installed, no bent pins, then replace the EEPROM. If a properly installed EEPROM continues to set B556, replace the BCM.

NOTE: The new EEPROM will have to be adjusted to the current mileage by the authorized Delco Electronics service center.

WHEN ALL DIAGNOSIS AND REPAIRS ARE COMPLETED, CLEAR CODES AND VERIFY OPERATION