Automatic Transaxle System Diagnosis System

When troubleshooting Europe On-Board Diagnostic (Euro-OBD) vehicles, the vehicle must be connected to an OBD scan tool (complying with ISO 15765-4). Various data output from the vehicle's ECM can then be read.

Euro-OBD regulations require that the vehicle's on-board computer illuminates the Malfunction Indicator Lamp (MIL) on the instrument panel when the computer detects a malfunction in:

1. The emission control system/components.
   

2. The powertrain control components (which affect vehicle emissions).
   

3. The computer.
   In addition, the applicable Diagnostic Trouble Codes (DTCs) prescribed by ISO 15765-4 are recorded in the ECM memory.
   If the malfunction does not reoccur in 3 consecutive trips, the MIL turns off automatically but the DTCs remain recorded in the ECM memory.
   

To check DTCs, connect the intelligent tester to the Data Link Connector 3 (DLC3) of the vehicle. The tester displays DTCs, the freeze frame data and a variety of the engine data.
The DTCs and freeze frame data can be erased with the tester (RAV4_ACA30 RM000000PDK0AIX.html).

When troubleshooting Multiplex On-Board Diagnostic (M-OBD) vehicles, the vehicle must be connected to the intelligent tester. Various data output from the ECM 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:

1. The emission control system/components.
   

2. The powertrain control components (which affect vehicle emissions).
   

3. The computer.
   In addition, the applicable DTCs are recorded in the ECM memory.
   If the malfunction does not reoccur in 3 consecutive trips, the MIL turns off automatically but the DTCs remain recorded in the ECM memory.
   

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.

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 drive cycle, the MIL is illuminated (2nd trip).

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 5 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.

The vehicle's ECM uses the ISO 15765-4 for communication protocol. The terminal arrangement of the DLC3 complies with ISO 15031-3 and matches the ISO 15765-4 format.

Terminals of DLC 3:

Terminal No.	Symbol	Name	Reference Terminal	Result	Condition
7	SIL	Bus "+" line	5 - Signal ground	Pulse generation	During transmission
4	CG	Chassis ground	Body ground	Below 1 Ω	Always
5	SG	Signal ground	Body ground	Below 1 Ω	Always
16	BAT	Battery positive	Body ground	11 to 14 V	Always
6	CANH	CAN bus line	CANL	54 to 69 Ω	IG switch OFF*
6	CANH	HIGH-level CAN bus line	Battery positive	6 KΩ or higher	IG switch OFF*
6	CANH	HIGH-level CAN bus line	CG	200 Ω or higher	IG switch OFF*
14	CANL	LOW-level CAN bus line	Battery positive	6 KΩ or higher	IG switch OFF*
14	CANL	LOW-level CAN bus line	CG	200 Ω or higher	IG switch OFF*

NOTICE:

*: Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the ignition switch, other switches or the doors.

HINT:

Connect the cable of the intelligent tester to the DLC3, turn the ignition switch ON and attempt to use the intelligent tester. If the screen displays a communication error message, a problem exists in the vehicle side or the tester side.

1. If the communication is normal when the tool is connected to another vehicle, inspect the DLC3 on the original vehicle.
   
2. If the communication is still impossible when the tool is connected to another vehicle, the problem is probably in the tool itself. Consult the Service Department listed in the tool's instruction manual.
   

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 (RAV4_ACA30 RM000000WZ109YX.html).

When the engine is started, the MIL should turn off.

For this vehicle, using the intelligent tester allows readiness codes corresponding to all DTCs to be read. When the diagnosis (normal or malfunctioning) has been completed, readiness codes are set.