M-OBD
When troubleshooting Multiplex On-Board Diagnostic (M-OBD) vehicles, the vehicle must be connected to the Intelligent Tester. Various data output from the TCM can then be read.
OBD regulations require that the vehicle's on-board computer illuminates the MIL 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
In addition to, the applicable DTCs are recorded in the TCM memory.
If the malfunction does not reoccur in 3 consecutive trips, the MIL turns off automatically but the DTCs remain recorded in the TCM memory.
To check DTCs, connect the Intelligent Tester to the Data Link Connector 3 (DLC3) of the vehicle.
The scan tool displays DTCs, the freeze frame data and a variety of the engine data.
The DTCs and freeze frame data can be erased with the scan tool Click here.
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 to technicians as an option. In check mode, "1-trip detection logic" is used for simulating malfunction symptoms and increasing the system's ability to detect malfunctions, including intermittent malfunctions (Intelligent Tester only).
2-TRIP DETECTION LOGIC
When a malfunction is first detected, the malfunction is temporarily stored in the TCM memory (1st trip). If the ignition switch is turned OFF and then ON again, and the same malfunction is detected again, the MIL will illuminate.
FREEZE FRAME DATA
Freeze frame data records the engine conditions (fuel system, calculated load, engine coolant temperature, fuel trim, engine speed, vehicle speed, etc.) when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, 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.
The Intelligent Tester records freeze frame data in five different instances: 1) 3 times before the DTC is set, 2) once when the DTC is set, and 3) once after the DTC is set. These data can be used to simulate the vehicle's condition around the time when the malfunction occurred. The data may help find the cause of the malfunction, or judge if the DTC is being caused by a temporary malfunction or not.
DLC3 (Data Link Connector 3)
The ECM uses ISO 15765-4 for communication. The terminal arrangement of the DLC3 complies with ISO 15031-3 and matches the ISO 15765-4 format.
| Symbols (Terminal No.) | Terminal Description | Condition | Specified Condition |
|---|---|---|---|
| SIL (7) - SG (5) | Bus "+" line | During transmission | Pulse generation |
| CG (4) - Body ground | Chassis ground | Always | Below 1 Ω |
| SG (5) - Body ground | Signal ground | Always | Below 1 Ω |
| BAT (16) - Body ground | Battery positive | Always | 11 to 14 V |
| CANH (6) - CANL (14) | CAN bus line | Ignition switch off* |
54 to 69 Ω |
| CANH (6) - CG (4) | HIGH-level CAN bus line | Ignition switch off* |
200 Ω or higher |
| CANL (14) - CG (4) | LOW-level CAN bus line | Ignition switch off* |
200 Ω or higher |
| CANH (6) - BAT (16) | HIGH-level CAN bus line | Ignition switch off* |
6 kΩ or higher |
| CANL (14) - BAT (16) | LOW-level CAN bus line | Ignition switch off* |
6 kΩ or higher |
Note
*: Before measuring the resistance, leave the vehicle as is for at least 1 minutes and do not operate the ignition switch, any other switches or the doors.
Connect the cable of the intelligent tester to the DLC3, turn the ignition switch ON and attempt to use the tester. If the display indicates that a communication error has occurred, there is a problem either with the vehicle or with the tester.
If communication is normal when the tester is connected to another vehicle, inspect the DLC3 of the original vehicle.
If communication is still not possible when the tester is connected to another vehicle, the problem may be in the tester itself. Consult the Service Department listed in the tester's instruction manual.
INSPECT BATTERY VOLTAGE
If voltage is below 11 V, replace the battery before proceeding.
CHECK MIL
Check that the MIL illuminates when turning the ignition switch ON.
If the MIL does not illuminate, there is a problem in the MIL circuit Click here for 1KD-FTV or Click here for 2KD-FTV).
When the engine is started, the MIL should turn off.
ALL READINESS
For this vehicle, using the Intelligent Tester allows readiness codes corresponding to all DTCs to be read. When diagnosis (normal or malfunctioning) has been complete, readiness codes are set.