DTCs P0300-P0308 Detection Logic
On DTCs P0300-P0308, MIL is set in 2 stages. If the ECM detects misfiring, strong enough to cause catalytic converter overheating, for any 200 revolutions of the engine, MIL will blink, but will not stay illuminated. If the ECM detects misfiring, strong enough to cause deterioration of catalytic converter, during 2 consecutive drive cycles, for any 1000 revolutions of the engine, MIL will illuminate.
Note. When road testing vehicle in CHECK mode (Lexus scan tool only), the Two Trip Detection Logic will not function. Also, MIL will illuminate first time a malfunction is detected.
DATA LINK CONNECTOR
OBD-II regulations (SAE J-1850) standardizes Data Link Connector (DLC) configurations. On all models, DLC No. 3 connector is located under left side of instrument panel. See appropriate illustration in appropriate SELF-DIAGNOSTICS article.
FREEZE-FRAME DATA
The ECM records engine operating condition when a misfire, fuel trim (mixture) malfunction or other malfunction (fuel system, calculated load, coolant temperature, fuel trim (mixture), engine speed, vehicle speed, etc.) exists. If more than one fault is detected, only data from the first malfunction is recorded. Recorded data is useful for determining conditions in which the malfunction occurs.
NORMAL Mode Code Retrieval
- Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 83) DLC No. 3 is located under left side of instrument panel. Turn ignition on with engine off. Turn scan tool on. Using scan tool manufacturer's instructions, check for DTCs and freeze-frame data.
- If scan tool displays UNABLE TO CONNECT TO VEHICLE, DLC No. 3 must be checked. See «DLC NO. 3 INSPECTION»(ref-3915-S40527800932000052400000) under SCAN TOOL PROBLEMS. If scan tool does not display UNABLE TO CONNECT TO VEHICLE, go to next step.
- Record any DTCs and freeze-frame data displayed for system diagnosis. If driveability problem exists and no DTCs are present, go to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom.
- If any DTCs are present, perform appropriate diagnostic test in appropriate SELF-DIAGNOSTICS article. See appropriate DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION table. For more information on freeze-frame data, see «FREEZE-FRAME DATA»(ref-3915-S16845358062000052400000) under INTRODUCTION. For information on 2-trip detection logic codes, see «TWO-TRIP DETECTION LOGIC»(ref-3915-S37457345012000052400000) under INTRODUCTION.
- After repairs for DTC have been completed, DTCs must be cleared from ECM memory. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-3915-S34745900872000052400000).
Scheme 83
SUMMARY
If no diagnostic trouble codes are present, driveability symptoms exist or intermittents exist, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent procedures.