TWO-TRIP DETECTION LOGIC
Two-trip detection logic is used to prevent erroneous malfunction detection. When a malfunction initially occurs, Diagnostic Trouble Code (DTC) is temporarily stored in ECM memory, but MIL on instrument panel will not illuminate.
The second time that a malfunction is detected, MIL on instrument panel will illuminate, provided ignition is turned off and then back on after first malfunction was detected. This is referred to as two-trip detection logic and only applies to specific DTCs.
DATA LINK CONNECTOR
OBD-II regulations standardize Data Link Connector (DLC) configurations. DLC No. 3 connector is located under left side of instrument panel. (Scheme 167)
Scheme 167
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, 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 167) 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.
- 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»(ref-151782) article for diagnosis by symptom.
- If any DTCs are present, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-151771-S42936466852003101500000). For more information on freeze-frame data, see «FREEZE-FRAME DATA»(ref-151771-S28640320182003010800000) under INTRODUCTION. For information on 2-trip detection logic codes, see «TWO-TRIP DETECTION LOGIC»(ref-151771-S29560308312003010800000) under INTRODUCTION.
- After repairs for DTC have been completed, DTCs must be cleared from ECM memory. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-151771-S35110467932003010800000).
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.
Confirmation Driving Pattern
For confirmation driving pattern (Scheme 168)
Scheme 168
For confirmation driving pattern (Scheme 169)
Scheme 169
- Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 167) Record any DTCs and FREEZE FRAME data.
- Switch scan tool to CHECK mode (Toyota hand-held tester only). Read value on misfire counter for each cylinder when idling. If the value is displayed on the misfire counter, skip the following procedure of confirmation driving.
- Drive vehicle several times with engine speed, load and its surrounding range shown with ENGINE SPD, CALC LOAD in FREEZE FRAME data or MISFIRE RPM and MISFIRE LOAD in scan tool data list. Turn ignition off after symptom is simulated the first time, then repeat test drive again (OBD-II scan tool only).
- Drive vehicle at specified engine speeds. See «DRIVING PATTERN»(ref-151771-S13845410322003010800000) table. If a misfire is detected, a DTC will set and misfire will be indicated in FREEZE FRAME data. Take care not to turn ignition off. Turning ignition switch off switches the diagnosis system from check (test) mode to normal mode and all DTCs, etc., are erased. DRIVING PATTERN RPM (1) Minutes Idling 3 1/2 1000 3 2000 1 1/2 3000 1 (1) Minimum specification is given.
- Check whether there is misfire or not by monitoring DTC and freeze frame data. After that, record them.
- Turn ignition switch off and wait at least 5 seconds.
Confirmation Engine Racing Pattern
- Connect OBD-II scan tool or hand-held tester to DLC3. (Scheme 167)
- Start engine and warm it up with all accessories switched off until water temperature becomes stable.
- Race engine at 2,500-3,000 RPM for approximately 3 minutes.
- Race engine at 3,000 RPM for 2 seconds and 2,000 RPM for 2 seconds alternately and check the waveform of the heated oxygen sensor (bank 1 sensor 2). (Scheme 170)
