For 1990-2009 cars

The automatic climate control head performs an electrically erasable programming read-only memory (EEPROM) checksum as part of its internal diagnostics as the HVAC is operating. When the EEPROM checksum does not equal a predetermined value, the DTC sets. The checksum is the contents of each memory location in EEPROM added together.

### DTC Parameters

EEPROM checksum error exists.

### Diagnostic Aids

If the DTC B1000 is set, clear DTCs using the scan tool. Cycle the ignition OFF. Wait 10 seconds. Cycle the ignition ON. If DTC B1000 remains the current code, replace the automatic climate control head using the procedure in the Saturn Service Stall System (SSS) user guide.