GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1998 🢒 DeVille 🢒 DTC 🢒 DTC B1658 EEPROM Checksum Error

Circuit Description

The memory seat module (MSM) calibrations are stored in the EEPROM. When the ignition is first turned ON, the MSM performs internal tests on the EEPROM and can determine the integrity of the non-volatile memory. The MSM compares the previously stored checksum with the checksum calculated when the ignition is first turned ON. If the two checksums do not match, the MSM will indicate a calibration malfunction (checksum error) is current.

Conditions for Setting the DTC
    • The stored checksum does not match the calculated checksum.
    • The MSM detects an internal memory malfunction (checksum error).
    • The condition occurs when the ignition is first turned ON.

Action Taken When the DTC Sets
    • The MSM stores a DTC B1658 in memory.
    • No driver warning message will be displayed for this DTC.
    • The MSM will use default values for any memory address in the EEPROM that is corrupt.

Conditions for Clearing the DTC
    • This DTC requires an ignition cycle in order to change from current to history.
    • The MSM no longer detects an internal memory malfunction (checksum error).
    • A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present.
    • Use the on-boards clearing DTCs feature.
    • Use a scan tool.

Diagnostic Aids

Since the EEPROM cannot be removed from the MSM and DTC B1658 is an internal MSM malfunction, the MSM may need to be replaced. Refer to the diagnostic table.

Test Description

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

  1. Perform the entire Power Seat Systems Diagnostic System Check before continuing with the diagnosis of this DTC.

    2.

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

    3.

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

Step

Action

Value(s)

Yes

No

1

Was the entire Power Seat Systems Diagnostic System Check performed?

--

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 .

Is the MSM replacement complete?

--

Go to Step 4

--

4

  1. Turn the ignition switch to the OFF position.
  2. Reconnect or install any connectors or components that were disconnected or removed.
  3. Turn the ignition switch to the ON position.
  4. Clear any DTCs. Refer to Diagnostic Trouble Code (DTC) Clearing .

Is the action complete?

--

Go to Diagnostic System Check - Power Seat Systems

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