Body Control System Diagnosis

DTC B1658 EEPROM Checksum Error:

CIRCUIT DESCRIPTION
The SBM calibrations are stored in Electronically Erasable Programmable Read Only Memory (EEPROM).

When you turn ON the ignition, the SBM performs internal tests on the EEPROM. The test may determine the integrity of the non-volatile memory. The SBM compares the previously stored checksum with a checksum calculated when the ignition turns ON. If the 2 checksums do not match, the SBM will indicate that a calibration malfunction (checksum error) is current.

CONDITIONS FOR SETTING THE DTC
^ The stored checksum does not match the calculated checksum.
^ The SBM detects an internal memory malfunction (checksum error).
^ The condition occurs when the ignition is first turned ON.

ACTION TAKEN WHEN THE DTC SETS
^ DTC B1658 stores in the SBM memory.
^ No driver warning message displays for this DTC.

CONDITIONS FOR CLEARING THE DTC
^ Under all fault conditions the ignition must be cycled before this DTC will change to history.
^ The SBM no longer detects an internal memory malfunction condition (write error).
^ A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present.

DIAGNOSTIC AIDS
^ The EEPROM is not removable from the SBM module.
^ A DTC B1658 is an internal malfunction to the SBM.