Diagnosis System
A340E AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM: DIAGNOSIS SYSTEM
1. DESCRIPTION
When troubleshooting On-Board Diagnostic (OBD II) vehicles, the vehicle must be connected to Techstream (complying with SAE J1987). Various data output from the vehicle's ECM can then be read.
OBD II regulations require that the vehicle's on-board computer illuminate the Malfunction Indicator Lamp (MIL) on the instrument panel when the computer detects a malfunction in:
The emission control system/components
The powertrain control components (which affect vehicle emissions)
The computers
In addition, the applicable Diagnostic Trouble Codes (DTCs) prescribed by SAE J2012 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 Techstream to the Data Link Connector 3 (DLC3) of the vehicle. Techstream displays DTCs, the freeze frame data and a variety of engine data.
The DTCs and freeze frame data can be erased with Techstream DTC Check / Clear.
In order to enhance OBD functions on vehicles and develop the Off-Board diagnosis system, CAN communication has been 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 simplification of the wire harness connection.
Since this system is equipped with CAN communication, connecting with Techstream is necessary to display any information from the ECM on the tester. (Also communication between Techstream and the ECM uses a CAN communication signal.) When confirming DTCs and any data of the ECM, connect Techstream to the DLC3.
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 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.
3. 2-TRIP DETECTION LOGIC
When a malfunction is first detected, the malfunction is temporarily stored in the ECM 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.
4. 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 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.
The ECM records engine conditions in the form of freeze frame data every 0.5 seconds. Using Techstream, five separate sets of freeze frame data, including the data values at the time when the DTC was set, can be checked.
3 data sets before the DTC was set
1 data set when the DTC was set
1 data set after the DTC was set
These data sets can be used to simulate the condition of the vehicle around the time when the malfunction occurred. The data may assist in identifying the cause of the malfunction, and in judging whether it was temporary or not.
5. DATA LINK CONNECTOR 3 (DLC3)
(a) The vehicle's ECM uses the ISO 15765-4 for communication protocol. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 15765-4 format.
Terminals of DLC3
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.
If the result is not as specified, the DLC3 may have a malfunction. Repair or replace the harness and connector.
HINT
Connect the cable of Techstream 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.
6. CHECK BATTERY VOLTAGE
Standard battery voltage:
11 to 14 V
If the voltage is below 11 V, replace the battery before proceeding.
7. CHECK MIL
(a) 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 Testing and Inspection.
(b) When the engine is started, the MIL should turn off.
8. ALL READINESS
For this vehicle, using Techstream allows readiness codes corresponding to all DTCs to be read. When diagnosis (normal or malfunctioning) has been completed, readiness codes are set. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.