GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1998 🢒 DeVille 🢒 DTC 🢒 DTC B1656 EEPROM Write Error

Circuit Description

The EEPROM write error detection is handled inside the control module. No external circuits are involved.

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

Action Taken When the DTC Sets
    • DTC B1656 is stored in the MMM memory.
    • No driver warning message will be displayed for this DTC.
    • The MMM 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 MMM no longer detects an internal write malfunction.
    • A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present.
    • Use the On-Board Clearing DTCs feature.
    • Use a scan tool.

Diagnostic Aids
    • If any of these DTCs are set, clear the DTCs and cycle the ignition.
    • If any of these DTCs are still current, replace the suspect module.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Perform the Power Door Diagnostic System Check.

    2.

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

    3.

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

Step

Action

Value(s)

Yes

No

1

Did you perform the Power Door Systems Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - Power Door Systems

2
  1. Turn on the ignition switch.
  2. Clear any DTCs. Refer to Diagnostic Trouble Code (DTC) Clearing in HVAC System - Automatic.
  3. Turn off the ignition switch.
  4. Turn on the ignition switch.

Is the DTC still present?

--

Go to Step 3

Go to Diagnostic System Check - Power Door Systems

3

Replace the memory mirror module (MMM).

Is the repair complete?

--

Go to Step 4

--

4
  1. Turn off the ignition switch.
  2. Connect or install any connector or components that were disconnected or removed.
  3. Turn on the ignition.
  4. Clear all of the DTCs. Refer to Diagnostic Trouble Code (DTC) Clearing in HVAC System - Automatic.

Are all of the DTCs cleared?

--

Go to Diagnostic System Check - Power Door Systems

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