Entertainment System Diagnosis

CIRCUIT DESCRIPTION
The radio (IRC) calibrations are stored in EEPROM (Electronically Erasable Programmable Read Only Memory). When the ignition is turned ON, the radio (IRC) performs internal tests on the EEPROM. The test determines the integrity of the non-volatile memory.

CONDITIONS FOR SETTING THE DTC
When the ignition is turned ON, the radio (IRC) performs internal tests on the EEPROM. The test determines the integrity of the non-volatile memory. The radio (IRC) compares the previously stored checksum with the checksum calculated when the ignition turns ON. If the 2 checksums do not match, the radio (IRC) will set DTC B1658 as current.

ACTION TAKEN WHEN THE DTC SETS
The radio (IRC) performs the following functions:
1. Clears all other stored DTCs.
2. Logs DTC B1658 as current.

CONDITIONS FOR CLEARING THE DTC
^ The ignition switch is cycled from OFF to ON and the checksum read by the radio (IRC) matches the previously stored one, DTC B1658 changes to history.
^ A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present.

DIAGNOSTIC AIDS
If DTC B1658 is set, clear the DTCs and cycle the ignition. If DTC B1658 is still current, replace the radio (IRC).