CAN Communication (Diagnostics - Introduction): Overview Lexus LX J200

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1. STEERING SYSTEM HANDLING PRECAUTIONS Care must be taken when replacing parts. Incorrect replacement could affect the performance of the steering system and result in hazards when driving.
2. SRS AIRBAG SYSTEM HANDLING PRECAUTIONS This vehicle is equipped with an SRS (Supplemental Restraint System), such as the driver airbag and front passenger airbag. Failure to carry out service operations in the correct sequence could cause unexpected SRS deployment during servicing and may lead to a serious accident. Before servicing (including installation/removal, inspection and replacement of parts), be sure to read the precautionary notice for the Supplemental Restraint System . Refer to «PRECAUTION»(ref-385233-S34574870702011021400000) .
3. BUS LINE REPAIR After repairing the bus line with solder, wrap the repaired part with vinyl tape . Refer to «ELECTRONIC CIRCUIT INSPECTION PROCEDURE»(ref-385196-S04310778802011021400000) . NOTE: The CANL bus line and CANH bus line must be installed together. When installing the CAN bus lines, make sure to twist them. CAN bus lines are likely to be influenced by noise if the bus lines are not twisted together. The difference in length between the CANL bus line and CANH bus line should be less than 100 mm (3.94 in.). Leave approximately 80 mm (3.15 in.) loose in the twisted wires around the connectors. Do not use by-pass wiring between the connectors. NOTE: The feature of the twisted wire harness will be lost if bypass wiring is used.
4. CONNECTOR HANDLING When inserting probes into a connector, insert them from the rear of the connector. Use a repair wire to check the connector if it is impossible to check resistance from the rear of the connector.

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1. *1: w/ Navigation System *2: w/o Navigation System *3: w/ Power Back Door System *4: w/ LEXUS Link System *5: w/ Wide View Front and Side Monitor System *6: w/ Dynamic Radar Cruise Control System

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HINT

1. The master cylinder solenoid (skid control ECU) stores steering sensor and yaw rate sensor DTCs and performs DTC communication by receiving information from the steering sensor and yaw rate sensor.
2. The ECM uses the CAN communication system to perform DTC communication instead of the conventional communication line (SIL).

SYSTEM DESCRIPTION

1. BRIEF DESCRIPTION The CAN (Controller Area Network) is a serial data communication system for real time application. It is a vehicle multiplex communication system which has a high communication speed (500 kbps, 250 kbps) and the ability to detect malfunctions. By pairing the CANH and CANL bus lines, the CAN performs communication based on differential voltages. Many ECUs (sensors) installed on the vehicle operate by sharing information and communicating with each other. The CAN has 2 resistors of 120 ohms which are necessary to communicate with the main wire.
2. DEFINITION OF TERMS Main wire The main wire is a wire harness between the 2 termination circuits on the bus (communication line). This is the main bus in the CAN communication system. Branch wire The branch wire is a wire harness which diverges from the main wire to an ECU or sensor. Termination circuits The termination circuit is a circuit which converts the communication current of the CAN communication into the bus voltage. It consists of a resistor and condenser. 2 termination circuits are necessary on a bus. CAN junction connector The CAN junction connector is designed so that it can be used with CAN communication which has a termination circuit and CAN communication which does not have a termination circuit.
3. CIRCUIT DESCRIPTION The V bus, movement control bus and MS bus each have termination circuits with resistance of 120 ohms x 2. High speed communication at 500 kbps and 250 kbps is possible.
4. ECU OR SENSOR WHICH COMMUNICATE VIA CAN COMMUNICATION SYSTEM Master cylinder solenoid (skid control ECU) Air conditioning amplifier ECM Main body ECU (cowl side junction block LH) Combination meter Center airbag sensor Display and navigation module display*1 Multi-display*2 Steering angle sensor Yaw rate sensor Seat belt control ECU*3 Parking assist ECU*4 Outer mirror control ECU Multiplex tilt and telescopic ECU Certification ECU (smart key ECU) Position control ECU and switch Tire pressure warning ECU Network gateway ECU 4WD control ECU No. 2 main body ECU Power back door unit (power back door ECU)*5 Bus buffer ECU*6 Distance control ECU*3 Steering control ECU Suspension control ECU AFS ECU (headlight swivel ECU) Windshield wiper ECU *1: w/ Navigation System *2: w/o Navigation System *3: w/ Dynamic Radar Cruise Control System *4: w/ Wide View Front and Side Monitor System *5: w/ Power Back Door System *6: w/ LEXUS Link System
5. DIAGNOSTIC CODES FOR CAN COMMUNICATION SYSTEM DTCs for the CAN communication system are as follows: U0073, U0100, U0101, U0114/38, U0122, U0123, U0124, U0126, U0127, U0129, U0130, U0132, U0140, U0141, U0148, U0151, U0199, U0208, U0230, U0327, U1002 (CAN MS BUS), U1002 (CAN No. 2 BUS), U1100, U1101, U1111, U1115, U1126, B1499, B2427, B2621, B2624 and C2179.
6. NOTES REGARDING TROUBLESHOOTING Trouble in the CAN bus (communication line) can be checked through the DLC3 (except when there is a wire break in the branch wire of the DLC3). DTCs regarding the CAN communication system can be checked using the Techstream. The CAN communication system cannot detect trouble in the branch line of the DLC3 even though the DLC3 is also connected to the CAN communication system.
7. HOW TO DISTINGUISH CAN JUNCTION CONNECTOR CONNECTOR In the CAN communication system, the shape of all connectors connected to the CAN junction connector is the same. The connectors connected to the CAN junction connector can be distinguished by the colors of the bus line and the connecting side of the connector. HINT: See "Terminals of ECU" . Refer to «TERMINALS OF ECU»(ref-385222-S00728644432011021400000) for bus line color or the type of connecting surface.