Automatic A/C-Heater Systems: Self-Diagnostics: Notes

An Electronic Control Unit (ECU), located within A/C-heater control assembly, monitors system circuits and stores Diagnostic Trouble Codes (DTC) in memory if problems are detected. All codes, except DTC B1422 and B1423, are stored in memory. Codes B1422 or B1423 are current if they are displayed. To retrieve stored codes, see RETRIEVING DIAGNOSTIC TROUBLE CODES . Codes are displayed on driver side temperature display. See Figure.