Maintenance: Service and Repair

The check engine lamp will be illuminated when the ignition switch is in the On position, when engine is not operating. When engine is started, the Check Engine lamp should go off. If lamp remains on, the Electronic Control Unit (ECU) has stored a code, or detected an abnormality in the system. After diagnosis and repair, place ignition switch in Off position, then clear codes stored in the ECU memory by removing the ECU-B fuse (1985-86 Camry), Stop fuse (1985-86 Celica and Supra) or EFI fuse (1987-92 models). These fuses must be removed for at least 10 seconds. On 1990-91 Supra models, remove the EFI (15A) fuse for at least 30 seconds. The colder the ambient temperature, the longer the fuse should be left out. The fuse is in the relay panel, located on the lefthand side of the engine compartment. Another method to erase stored codes is to disconnect the battery negative cable. This method will also erase any other stored memories, such as the clock and radio.