GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Park Avenue 🢒 Body and Accessories 🢒 Doors 🢒 DTC B1656 EEPROM Write Error

Circuit Description

The memory seat module (MSM) performs internal tests on the electrically erasable programmable read only memory (EEPROM) each time that the MSM performs a write function to a memory address in the EEPROM. The MSM reads back the data that has been written and compares the it to the data. If the data does not match after 3 consecutive write and verify attempts, the MSM will indicate that a write malfunction is current.

Conditions for Setting the DTC
    • The data read back after a write does not match the data being written 3 consecutive times.
    • The MSM detects an internal write malfunction.
    • The condition must occur when data is being written.

Action Taken When the DTC Sets
    • Stores a DTC B1656 in the MSM memory.
    • No driver warning message displays for this diagnostic trouble code (DTC).
    • The MSM stores the value being written in another memory address in the EEPROM.

Conditions for Clearing the DTC
    • This DTC requires a successful write in order to change from current to history.
    • The MSM no longer detects an internal write malfunction.
    • A history DTC clears after 50 consecutive ignition cycles if the condition for the malfunction is no longer present.
    • Use a scan tool.

Diagnostic Aids

You may need to replace the MSM because of the following factors:

    • You cannot remove the EEPROM from the MSM.
    • DTC B1656 is an internal MSM malfunction.

Test Description

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

  1. Perform the entire power seat systems diagnostic system check before you continue with the diagnosis of this diagnostic trouble code (DTC).

    2.

  2. Clear all of the DTCs. Cycle the ignition in order to verify that the DTC did not falsely set.

    3.

  3. Clear all of the DTCs after you complete the repair procedure.

Step

Action

Value(s)

Yes

No

1

Did you perform the Power Seat Systems Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Power Seat Systems

2

  1. Turn the ignition switch to the ON position.
  2. Clear any DTCs. Refer to Diagnostic Trouble Code (DTC) Clearing .
  3. Turn the ignition switch to the OFF position.
  4. Turn the ignition switch to the ON position.

Is the DTC still present?

--

Go to Step 3

Go to Diagnostic System Check - Power Seat Systems

3

Replace the memory seat module (MSM). Refer to Memory Seat Control Module Replacement in Seats.

Did you complete the repair?

--

Go to Step 4

--

4

  1. Turn the ignition switch to the OFF position.
  2. Reconnect or install any of the connectors or the components that were disconnected or removed.
  3. Turn the ignition switch to the ON position.
  4. Clear any DTCs. Refer to Clearing DTCs.

Are all of the DTCs cleared?

--

Go to Diagnostic System Check - Power Seat Systems

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