CAN Communication System - Diagnosis: Overview Lexus LS III рестайлинг

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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 hazardous driving.
2. SRS AIRBAG SYSTEM HANDLING PRECAUTIONS The LEXUS LS430 is equipped with an SRS (Supplemental Restraint System) such as the driver's airbag and front passenger airbag. Failure to carry out service operations in correct sequence could cause unexpected SRS deployment during servicing and may lead to a serious accident. Before servicing (including removal or installation of parts, inspection or replacement), be sure to read the precautionary notice for the supplemental restraint system (See «AIR BAG SAFETY PRECAUTIONS» ).
3. BUS LINE REPAIR After repairing the bus line with solder, wrap the repaired part with vinyl tape (see «REPAIR INSTRUCTION» ). NOTE: The CANL bus line and CANH bus line must be installed together all the time. When installing, make sure to twist them. CAN bus lines are likely to be influenced by noise if the bus lines are not twisted. The difference in length of the CANL bus line and CANH bus line should be within 100 mm (3.937 in.). Leave approximately 80 mm (3.150 in.) loose in the twist around the connector. Do not use bypass wiring between the connectors. NOTE: The feature of the twisted wire harness will be lost if you use bypass wiring.
4. CONNECTOR HANDLING When inserting tester 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 continuity from the rear of the connector.
5. PRECAUTION FOR DISCONNECTING THE BATTERY CABLE NOTE: When disconnecting the negative (-) battery terminal, initialize the following system after the terminal is reconnected. SYSTEM NAME System Name See Front Power Seat Control System «FRONT POWER SEAT CONTROL SYSTEM»

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HINT

1. The position of the terminus circuit differs in vehicles with and without the LEXUS navigation system.
2. The skid control ECU with actuator detects and stores steering sensor and yaw rate sensor DTCs and performs DTC communication by receiving information from the steering sensor and yaw rate sensor.
3. The ECM detects and stores distance control ECU DTCs, and performs DTC communication by receiving information from the distance control ECU.
4. 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 multiplex communication system equipped for a vehicle and has a high communication speed (500 kbps) and the function to detect malfunctions. By pairing the CANH and CANL bus lines, the CAN performs communication based on differential voltage. Many ECUS (sensors) installed on the vehicle operate by sharing information and communicating with each other. The CAN has two resistors of 120 ohms which are necessary to communicate with the main bus line.
2. DEFINITION OF TERMS Main bus line The main bus line is the wire harness between the two terminus circuits on the bus (communication line). This is the main bus in the CAN communication system. Sub bus line The sub bus line is the wire harness which diverges from the main bus line to the ECU or sensor. Terminus circuit The terminus circuit is a circuit which is placed to convert communication current of the CAN communication into bus voltage. It consists of a resistor and condenser. Two terminus circuits are necessary on a bus. CAN J/C The CAN J/C is a junction designed for CAN communication, which stores a terminus circuit.
3. ECUS OR SENSORS WHICH COMMUNICATE THROUGH CAN COMMUNICATION SYSTEM Skid Control ECU with Actuator Yaw Rate Sensor Steering Sensor Television Camera ECU Seat Belt Control ECU Distance Control ECU Suspension Control ECU ECM Gateway ECU
4. DIAGNOSTIC CODE FOR CAN COMMUNICATION SYSTEM DTCs for the CAN communication system are as follows: U0073, U0100, U0101, U0122, U0123, U0124, U0126, U0132, U0145, U1101
5. REMARK FOR TROUBLESHOOTING Trouble in the CAN bus (communication line) can be checked from the DLC3 (except when there is a wire break other than in the sub bus line of the DLC3). NOTE: Do not insert the tester directly into the DLC3 connector. Be sure to use a service wire. DTCs regarding the CAN communication system can be checked using the hand-held tester via the CAN VIM. The CAN communication system cannot detect trouble in the sub bus line of the DLC3 even though the DLC3 is also connected to the CAN communication system.
6. HOW TO DISTINGUISH THE CAN J/C CONNECTOR In the CAN communication system, the shape of all connectors connected to the CAN J/C is the same. The connectors connected to the CAN J/C can be distinguished by the colors of the bus lines and the connecting side of the connector. HINT: See "TERMINALS OF ECU" (See «TERMINALS OF ECU» ) for bus line color or the type of connecting surface.

MODE DESCRIPTION

MODE DESCRIPTION

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1. CHECK CAN BUS LINE FOR DISCONNECTION (SKID CONTROL ECU SUB BUS LINE) Turn the ignition switch to the LOCK position. Disconnect the skid control ECU connector (S42). Measure the resistance according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified value S42-11 (GANH) - S42-25 (CANL) Ignition Switch OFF 54 to 69 ohms NG: REPAIR OR REPLACE SKID CONTROL ECU SUB BUS LINE OR CONNECTOR (CAN-H, CAN-L) OK: Go to next page.
2. CHECK WIRE HARNESS (IG, GND1, GND2) Measure the resistance according to the value (s) in the table below. Measure the voltage according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified value S42-1 (GND2) - Body ground Always Below 1 ohms S42-32 (GND1) - Body ground Always Below 1 ohms S42-46 (IG1) - Body ground Ignition Switch ON 10 to 14 V NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR OK: REPLACE SKID CONTROL ECU WITH ACTUATOR (See «REPLACEMENT»(/lexus/ls/iii-2003-2006/remont/anti-locktraction-control/#abs-traction-actuator) )

MODE DESCRIPTION

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1. CHECK CAN BUS LINE FOR DISCONNECTION (STEERING SENSOR SUB BUS LINE) Turn the ignition switch to the LOCK position. Disconnect the steering sensor connector (S16). Measure the resistance according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified value S16-10 (CANH) - S16-9 (CANL) Ignition Switch OFF 54 to 69 ohms NG: REPAIR OR REPLACE STEERING SENSOR SUB BUS LINE OR CONNECTOR (CAN-H, CAN -L) OK: Go to next step.
2. CHECK WIRE HARNESS (IG1, ESS) Measure the resistance according to the value (s) in the table below. Measure the voltage according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified condition S16-2 (ESS) - Body ground Always Below 1 ohms S16-1 (IG1) - Body ground Ignition Switch ON 10 to 14 V NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR OK: REPLACE STEERING SENSOR (See «REPLACEMENT»(/lexus/ls/iii-2003-2006/remont/anti-locktraction-control/#steering-sensor) )

MODE DESCRIPTION

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1. CHECK CAN BUS LINE FOR DISCONNECTION (YAW RATE SENSOR SUB BUS LINE) Turn the ignition switch to the LOCK position. Disconnect the yaw rate sensor connector (Y1). Measure the resistance according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified value Y1-2 (CANL) - Y1-3 (CANH) Ignition Switch OFF 54 to 69 ohms NG: REPAIR OR REPLACE YAW RATE SENSOR SUB BUS LINE OR CONNECTOR (CAN-H, CAN-L) OK: Go to next step.
2. CHECK WIRE HARNESS (IG, GND) Measure the resistance according to the value (s) in the table below. Measure the voltage according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified condition Y1-1 (GND) - Body ground Always Below 1 ohms Y1-5 (IG) - Body ground Ignition Switch ON 10 to 14 V NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: REPLACE YAW RATE SENSOR (See «YAWRATE SENSOR»(/lexus/ls/iii-2003-2006/remont/anti-locktraction-control/#yawrate-sensor) )

MODE DESCRIPTION

Note. This is not applicable to a vehicle without a dynamic radar/laser cruise control system.

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1. CHECK CAN BUS LINE FOR DISCONNECTION (DISTANCE CONTROL ECU SUB BUS LINE) Turn the ignition switch to the LOCK position. Disconnect the distance control ECU connector (D2). Measure the resistance according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified value D2-8 (CANH) - D2-9 (CANL) Ignition Switch OFF 54 to 69 ohms NG: REPAIR OR REPLACE DISTANCE CONTROL ECU SUB BUS LINE OR CONNECTOR (CAN-H, CAN-L) OK: Go to next step.
2. CHECK WIRE HARNESS (+B, GND) Measure the resistance according to the value (s) in the table below. Measure the voltage according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified condition D2-12 (GND) - Body ground Always Below 1 ohms D2-1 (+B) - Body ground Ignition Switch ON 10 to 14 V NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR OK: REPLACE DISTANCE CONTROL ECU ASSY (See «REPLACEMENT» )

MODE DESCRIPTION

Note. This is not applicable to a vehicle without a LEXUS navigation system.

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1. CHECK CAN BUS LINE FOR DISCONNECTION (TELEVISION CAMERA ECU SUB BUS LINE) Turn the ignition switch to the LOCK position. Disconnect the television camera ECU connector (T24). Measure the resistance according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified value T24-8 (CANH) - T24-7 (CANL) Ignition Switch OFF 54 to 69 ohms NG: REPAIR OR REPLACE TELEVISION CAMERA ECU SUB BUS LINE OR CONNECTOR (CAN-H, CAN-L) OK: Go to next step.
2. CHECK WIRE HARNESS (IG, +B, ACC, GND1) Reconnect the television camera ECU connector (T24). Disconnect the television camera ECU connector (T25). Measure the resistance according to the value (s) in the table below. Measure the voltage according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified condition T25-8 (GND1) - Body ground Always Below 1 ohms T25-1 (+B) - Body ground Always 10 to 14 V T25-2 (IG) - Body ground Ignition Switch ON 10 to 14 V T25-5 (ACC) - Body ground Ignition Switch ACC 10 to 14 V NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR OK: REPLACE TELEVISION CAMERA ECU (See «REPLACEMENT» )

MODE DESCRIPTION

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1. CHECK CAN BUS LINE FOR DISCONNECTION (ECM SUB BUS LINE) Turn the ignition switch to the LOCK position. Disconnect the ECM connector (E3). Measure the resistance according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified value E3-25 (CANH)" - E3-24 (CANL) Ignition Switch OFF 54 to 69 ohms NG: REPAIR OR REPLACE ECM SUB BUS LINE OR CONNECTOR (CAN-H, CAN-L) OK: Go to next step.
2. CHECK WIRE HARNESS (+B1, +B, E1) Disconnect the ECM connector (E6). Measure the resistance according to the value (s) in the table below. Measure the voltage according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified condition E6-7 (E1) - Body ground Always Below 1 ohms E3-5 (+B1) - Body ground Ignition Switch ON 10 to 14 V E3-6 (+B) - Body ground Ignition Switch ON 10 to 14 V NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR OK: REPLACE ECM (See «REPLACEMENT» )

MODE DESCRIPTION

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1. CHECK CAN BUS LINE FOR DISCONNECTION (GATEWAY ECU SUB BUS LINE) Turn the ignition switch to the LOCK position. Disconnect the gateway ECU connector (G3). Measure the resistance according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified value G3-17 (CA1H) - G3-18 (CA1L) Ignition Switch OFF 54 to 69 ohms NG: REPAIR OR REPLACE GATEWAY ECU SUB BUS LINE OR CONNECTOR (CAN-H, CAN-L) OK: Go to next step.
2. CHECK WIRE HARNESS (BATT, ACC, IG, CG, GND) Measure the resistance according to the value (s) in the table below. Measure the voltage according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified condition G3-9 (CG) - Body ground Always Below 1 ohms G3-24 (GND) - Body ground Always Below 1 ohms G3-10 (BATT) - Body ground Always 10 to 14 V G3-2 (ACC) - Body ground Ignition Switch ACC 10 to 14 V G3-1 (IG) - Body ground Ignition Switch ON 10 to 14 V NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR OK: REPLACE GATEWAY ECU

MODE DESCRIPTION

Note. This is not applicable to a vehicle without an air suspension system.

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1. CHECK CAN BUS LINE FOR DISCONNECTION (SUSPENSION CONTROL ECU SUB BUS LINE) Turn the ignition switch to the LOCK position. Disconnect the suspension control ECU connector (A20). Measure the resistance according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified value A20-7 (CANH) - A20-8 (CANL) Ignition Switch OFF 54 to 69 ohms NG: REPAIR OR REPLACE SUSPENSION CONTROL ECU SUB BUS LINE OR CONNECTOR (CAN-H, CAN-L) OK: Go to next step.
2. CHECK WIRE HARNESS (B, GND) Measure the resistance according to the value (s) in the table below. Measure the voltage according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified value A20-4 (GND) - Body ground Always Below 1 ohms A20-1 (B) - Body ground Ignition Switch ON 10 to 14 V NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR OK: REPLACE SUSPENSION CONTROL ECU (See «REPLACEMENT» )

MODE DESCRIPTION

Note. This is not applicable to a vehicle without a Pre-collision safety system.

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1. CHECK CAN BUS LINE FOR DISCONNECTION (SEAT BELT CONTROL ECU SUB BUS LINE) Turn the ignition switch to the LOCK position. Disconnect the seat belt control ECU connector (S63). Measure the resistance according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified value S63-4 (CANH) - S63-6 (CANL) Ignition Switch OFF 54 to 69 ohms NG: REPAIR OR REPLACE SEAT BELT CONTROL ECU SUB BUS LINE OR CONNECTOR OK: Go to next step.
2. CHECK WIRE HARNESS (IG, GND) Disconnect the seat belt control ECU connector (S63). Measure the resistance according to the value (s) in the table below. Measure the voltage according to the value (s) in the table below. Standard: TESTER CONNECTION CHART Tester connection Condition Specified condition S63-18 (GND) - Body ground Always Below 1 ohms S63-9 (+B) - Body ground Always 10 to 14 V S63-3 (IG) - Body ground Ignition Switch ON 10 to 14 V NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR OK: REPLACE SEAT BELT CONTROL ECU

See also:
• REPLACEMENT
• REPLACEMENT
• YAWRATE SENSOR