B1658

CIRCUIT DESCRIPTION
The Integrated Radio Controller (IRC) keeps an EEPROM value that contains a checksum for each of its EEPROM blocks. These values are not included in the checksums of the blocks, but is a static, or read only value. The IRC computes a checksum for the EEPROM block and compares it to a checksum stored in the EEPROM. If the values do not match, then the IRC sets DTC B1658.

CONDITIONS FOR SETTING THE DTC
^ The stored checksum does not match the calculated checksum.
^ The IRC detects an internal memory malfunction (checksum error).
^ The condition must occur when the ignition is first turned ON or within 2.5 seconds of the ignition being turned ON.

ACTION TAKEN WHEN THE DTC SETS
^ DTC B1658 is stored in the IRC memory.
^ No driver warning message will be displayed for this DTC.
^ The IRC 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 a current DTC to a history DTC.
^ The IRC 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.

DIAGNOSTIC AIDS
^ Since the EEPROM cannot be removed from the IRC and DTC B1658 is an internal IRC malfunction, the IRC needs to be replaced.
^ Replace the radio.