Diagnosis System
1NZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: DIAGNOSIS SYSTEM
1. DESCRIPTION
* When troubleshooting OBD II (On-Board Diagnostics) vehicles, a Techstream (complying with SAE J1987) must be connected to the DLC3 (Data Link Connector 3) of the vehicle. Various data in the vehicle's ECM (Engine Control Module) can be then read.
* OBD II regulations require that the vehicle's on-board computer illuminate the MIL (Malfunction Indicator Lamp) on the instrument panel when the computer detects a malfunction in:
* The emission control system components.
* The power train control components (which affect vehicle emissions).
* The computer itself.
* In addition, if the applicable DTCs (Diagnostic Trouble Codes) prescribed by SAE J2012 are not recorded on 3 consecutive trips, the MIL turns off automatically but the DTCs remain recorded in the ECM memory.
* To check DTCs, connect the Techstream to the DLC3. The Techstream displays DTCs, freeze frame data, and a variety of the engine data. The DTCs and freeze frame data can be erased with the Techstream DTC Check / Clear.
* In order to enhance OBD function on vehicles and develop the OFF-Board diagnosis system, CAN communication is introduced in this system (CAN: Controller Area Network). It minimizes the gap between technician skills and vehicle technology. CAN is a network, which uses a pair of data transmission lines, spanning multiple computers and sensors. It allows high speed communication between the systems and simplifies the wire harness connection.
2. NORMAL MODE AND CHECK MODE
The diagnosis system operates in normal mode during normal vehicle use. In normal mode, 2 trip detection logic is used to ensure accurate detection of malfunctions. Check mode is also available as an option for technicians. In check mode, 1 trip detection logic is used for simulating malfunction symptoms and increasing the system's ability to detect malfunctions, including intermittent problems (Techstream only) Check Mode Procedure.
3. 2 TRIP DETECTION LOGIC
When a malfunction is first detected, the malfunction is temporarily stored in the ECM memory (1st trip). If the same malfunction is detected during the next subsequent drive cycle, the MIL is illuminated (2nd trip).
4. FREEZE FRAME DATA
Freeze frame data record the engine conditions (fuel system, calculated engine load, engine coolant temperature, fuel trim, engine speed, vehicle speed, etc.) when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data, from the time the malfunction occurred.
5. DLC3 (Data Link Connector 3)
(a) The ECM uses ISO 15765-4 for communication. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 15765-4 format.
NOTICE:
*: Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the ignition switch, any other switches or the doors.
HINT
The DLC3 is the interface prepared for reading various data from the vehicle's ECM. After connecting the cable of a Techstream, turn the ignition switch to ON and turn the Techstream on. If the display indicates that a communication error has occurred, there is a problem either the vehicle or tester. In order to identify the location of the problem, connect the Techstream to another vehicle.
If communication is normal: Inspect the DLC3 on the original vehicle.
If communication is still not possible: The problem is probably in the Techstream itself. Consult the Service Department listed in the instruction manual for the Techstream.
6. BATTERY VOLTAGE
Standard voltage:
11 to 14 V
If the voltage is below 11 V, replace or recharge the battery before proceeding
7. MIL (Malfunction Indicator Lamp)
(a) The MIL is illuminated when the ignition switch is first turned to ON (the engine is not running).
(b) The MIL should turn off when the engine is started. If the MIL remains illuminated, the diagnosis system has detected a malfunction or abnormality in the system.
HINT
If the MIL is not illuminated when the ignition switch is first turned to ON, check the MIL circuit MIL Circuit.
8. ALL READINESS
HINT
* With All Readiness you can check whether or not the DTC judgment has been completed by using the Techstream.
* You should check All Readiness after simulating malfunction symptoms or for validation after finishing repairs.
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Clear DTCs DTC Check / Clear.
(e) Turn the ignition switch off and wait for at least 30 seconds.
(f) Turn the ignition switch to ON and turn the Techstream on.
(g) Perform the DTC judgment driving pattern to run the DTC judgment.
(h) Enter the following menus: Powertrain / Engine / Utility / All Readiness.
(i) Input the DTCs to be confirmed.
(j) Check the DTC judgment result.
Techstream:
