TWO-TRIP DETECTION LOGIC
When a malfunction initially occurs, Diagnostic Trouble Code (DTC) will be temporarily stored in ECM memory but Malfunction Indicator Light (MIL) will not illuminate. The second time malfunction is detected, MIL 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. When road testing vehicle in CHECK mode using Toyota hand-held tester, two-trip detection logic will not function and MIL will illuminate the first time a malfunction is detected.
DATA LINK CONNECTOR
OBD-II regulations (SAE J-1962) standardizes configuration of Data Link Connector (DLC3). DLC3 is located at driver's side of instrument panel. (Scheme 99)
Scheme 99
FREEZE FRAME DATA
Engine Control Module (ECM) records engine operating conditions when a misfire or fuel trim (mixture) malfunction or when various other malfunctions exist. ECM records engine operating conditions for the fuel system, calculated load, engine coolant temperature, engine speed, vehicle speed, etc. when a malfunction exists. This information is referred to as freeze frame data. If more than one Diagnostic Trouble Code (DTC) exists, only freeze frame data for the first DTC is recorded. Freeze frame data is useful for determining conditions when a malfunction occurred. OBD-II scan tool or Toyota hand-held tester may be used to read freeze frame data.
ENGINE CONTROL MODULE PROGRAMMING
An engine immobilizer system may be used. On models equipped with engine immobilizer system, if Engine Control Module (ECM) is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. Models equipped with engine immobilizer system may be identified by looking at the ignition key. On models equipped with engine immobilizer system, the top of the ignition key is thicker than a standard ignition key, as a transponder chip is incorporated into the top of the ignition key. For programming procedures, see COMPUTER RELEARN PROCEDURES - TOYOTA article in GENERAL INFORMATION, or appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT.
Scheme 100
- If Toyota hand-held tester or scan tool displays UNABLE TO CONNECT TO VEHICLE when hand-held tester or scan tool is connected to Data Link Connector (DLC3), try hand-held tester or scan tool on another vehicle. If hand-held tester or scan tool operates on another vehicle, go to next step. If hand-held tester or scan tool does not operate on another vehicle, problem is probably with hand-held tester or scan tool.
- Check voltage and resistance between ground and specified terminal on DLC3. See «DATA LINK CONNECTOR (DLC3) VOLTAGE & RESISTANCE SPECIFICATIONS»(ref-151976-S03408063232003010900000) table. (Scheme 100) If voltage or resistance are not within specification, check wiring circuit. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article. DATA LINK CONNECTOR (DLC3) VOLTAGE & RESISTANCE SPECIFICATIONS Terminal No. (Circuit) Specification 4 (Chassis Ground) 1 Ohm Or Less 5 (Signal Ground) 1 Ohm Or Less 7 (BUS Communication) (1) 16 (Battery Voltage) 9-14 Volts (1) Pulse generation should exist during information transmission from Engine Control Module (ECM).
SUMMARY
If no Diagnostic Trouble Codes (DTC) are present and a no start condition exists, proceed to BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If no DTCs are present and a driveability condition exists, proceed to TROUBLESHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, ENGINE STALLS, etc.).
Possible Causes
For possible causes (Scheme 101)
