System Overview

WARNING: This page is about a different car, the 2003 Toyota Camry Solara. However, it is still accessible from the selected car via links, so may be relevant.

When trouble shooting OBD II vehicles, the only difference from the usual trouble shooting procedure is that you need to connect the vehicle to the hand-held tester or OBD II scan tool complying with SAE J1978, and read off various data output from the vehicle's ECM.

OBD II regulations require that the vehicle's onboard computer lights up the malfunction indicator light (MIL) on the instrument panel when the computer detects a malfunction in the emission control system/components or in the powertrain control components which affect vehicle emissions, or a malfunction in the computer. In addition to the MIL lighting up when a malfunction is detected, the applicable diagnostic trouble code (DTCs) prescribed by SAE J2012 are recorded in the ECM memory. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .

If the malfunction does not reoccur in the 3 consecutive trips, the MIL goes off automatically but the DTCs remain in the ECM memory.

To check the DTCs, connect the hand-held tester or OBD II scan tool to the data link connector No. 3 (DLC3) of the vehicle. See Figure. The hand-held tester or OBD II scan tool also enables you to erase the DTCs and check the freeze frame data and various forms of engine data (for operating instructions, see the OBD II scan tool's instruction book). DTCs include SAE controlled codes and manufacturer controlled codes. SAE controlled codes must be set as prescribed by the SAE, while manufacturer controlled codes can be set freely by a manufacturer within the prescribed limits. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .