CAN Communication System (Diagnostics - Introduction): Overview Scion tC II рестайлинг

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1. IGNITION SWITCH EXPRESSION HINT: The type of ignition switch used on this model differs according to the specifications of the vehicle. The expressions listed in the table below are used in this Service Information. Expression Ignition Switch (Position) Engine Switch (Condition) Ignition Switch off LOCK Off (Lock) Ignition Switch ON ON On (IG) Ignition Switch ACC ACC On (ACC) Engine Start START On (Start)
2. 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.
3. SRS AIRBAG SYSTEM HANDLING PRECAUTIONS This vehicle is equipped with an SRS (Supplemental Restraint System), which includes components such as the driver airbag and front passenger side 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 [05/2013 - 01/2014]»(ref-615289-S06154869092014050900000).
4. BUS LINE REPAIR After repairing the bus line with solder, wrap the repaired part with vinyl tape. Refer to «ELECTRONIC CIRCUIT INSPECTION PROCEDURE [05/2013 - ]»(ref-615109-S05659225472014050900000). 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. 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 protective effect of the twisted wire harness will be lost if bypass wiring is used. TEXT IN ILLUSTRATION *1 By-pass Wire
5. CONNECTOR HANDLING When inserting probes into a connector, insert them from the rear of the connector. TEXT IN ILLUSTRATION *1 Tester Probe Use a repair wire to check the connector if it is impossible to check resistance from the rear of the connector. TEXT IN ILLUSTRATION *1 Repair Wire

SYSTEM DESCRIPTION [05/2013 - 01/2014]

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) and the ability to detection 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 communication with each other. The CAN has 2 resistors of 120 ohms which are necessary to communicate using the main wire.
2. DEFINITION OF TERMS CAN main wire The CAN main wire is a wire harness between the 2 termination circuits on the bus (communication line). This is the CAN main bus in the CAN communication system. CAN branch wire The CAN branch wire is a wire harness which diverges from the main wire to an ECU or sensor. Termination circuit 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 capacitor. 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 V1 bus, power management bus and powertrain bus each have termination circuits with resistance of 120 ohms X 2. High speed communication at 500 kbps is possible.
4. ECUS OR SENSORS WHICH COMMUNICATE VIA CAN COMMUNICATION SYSTEM ECM Power source control ECU*1 Main body ECU (multiplex network body ECU) Brake actuator assembly (skid control ECU) DLC3 Spiral with sensor cable sub-assembly (steering angle sensor) Power steering ECU assembly Certification ECU (smart key ECU assembly)*1 Airbag sensor assembly Combination meter assembly Air conditioning amplifier assembly Transmission control ECU assembly*2 *1: w/ Smart Key System *2: for Automatic Transaxle
5. DIAGNOSTIC CODES FOR CAN COMMUNICATION SYSTEM DTCs for the CAN communication system are as follows: U0073, U0100, U0101, U0124, U0126, U0129, U0131, U0142, U0151 and U0155.
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 CAN 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 CAN branch wire of the DLC3 even though the DLC3 is also connected to the CAN communication system.
7. HOW TO DISTINGUISH CAN JUNCTION CONNECTOR CONNECTORS 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 [05/2013 - 01/2014]»(ref-615285-S29707822172014050900000) for bus line color or the type of connecting surface.

SYSTEM DESCRIPTION [01/2014 - ]

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) and the ability to detection 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 communication with each other. The CAN has 2 resistors of 120 ohms which are necessary to communicate using the main wire.
2. DEFINITION OF TERMS CAN main wire The CAN main wire is a wire harness between the 2 termination circuits on the bus (communication line). This is the CAN main bus in the CAN communication system. CAN branch wire The CAN branch wire is a wire harness which diverges from the main wire to an ECU or sensor. Termination circuit 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 capacitor. 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 V1 bus, power management bus and powertrain bus each have termination circuits with resistance of 120 ohms X 2. High speed communication at 500 kbps is possible.
4. ECUS OR SENSORS WHICH COMMUNICATE VIA CAN COMMUNICATION SYSTEM ECM Power source control ECU*1 Main body ECU (multiplex network body ECU) Brake actuator assembly (skid control ECU) DLC3 Spiral with sensor cable sub-assembly (steering angle sensor) Power steering ECU assembly Certification ECU (smart key ECU assembly)*1 Airbag sensor assembly Combination meter assembly Air conditioning amplifier assembly Transmission control ECU assembly*2 *1: w/ Smart Key System *2: for Automatic Transaxle
5. DIAGNOSTIC CODES FOR CAN COMMUNICATION SYSTEM DTCs for the CAN communication system are as follows: U0073, U0100, U0101, U0124, U0126, U0129, U0131, U0142, U0151 and U0155.
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 CAN 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 CAN branch wire of the DLC3 even though the DLC3 is also connected to the CAN communication system.
7. HOW TO DISTINGUISH CAN JUNCTION CONNECTOR CONNECTORS 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 [01/2014 - ]»(ref-615285-S40343633732014050900000) for bus line color or the type of connecting surface.

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1. IMPORTANT POINT CONCERNING TROUBLESHOOTING WARNING: Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the airbag system. NOTE: Refer to the troubleshooting procedures of each system if DTCs regarding the CAN communication system are not output. Before measuring the resistance, leave the vehicle for at least 1 minute and do not operate the ignition switch, any switches or any doors. If doors need to be opened in order to check connectors, open the doors and leave them open. When disconnecting the cable, some systems need to be initialized after the cable is reconnected. Refer to «INITIALIZATION [05/2013 - 01/2014]»(ref-615109-S22240423792014050900000). HINT: Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation. *: Use the Techstream. DTCs indicating a CAN communication malfunction are also stored due to internal or power source-related problems in ECUs or sensors of systems using CAN communication. Therefore, check whether codes indicating internal or power source-related problems in those systems are output together with the CAN communication DTCs. It is possible to inspect the circuit of the DLC3 CAN branch wire or V1 bus main line for malfunctions by inspecting the terminals of the DLC3 using SST. NOTE: It is only possible to inspect CAN branch wires to ECUs (sensors) or the V1 bus from the DLC3. It is possible to check which ECUs (sensors) are not able to communicate via CAN communication by checking the "Bus Check" function of the Techstream (when the DLC3 CAN branch wire and V1 bus CAN main wire are normal). HINT: When checking "Bus Check", ECUs (sensors) whose CAN branch wire is open or that cannot communicate via CAN communication do not respond to the Techstream (they are not displayed on the screen). When checking "Bus Check", if a DTC indicating a CAN communication malfunction is output even though all ECUs (sensors) respond (they are displayed on the screen), use the DTC combination table to determine the suspected trouble area and perform symptom simulation. For past malfunctions of the V1 bus, the ECUs (sensors) which cannot communicate via CAN communication can be determined from the combination of CAN communication DTCs that are output. The power source control ECU (Power Source Control) detects malfunctions in the power management bus circuit and outputs DTCs depending on the malfunctioning areas. The ECUs (sensors) which cannot communicate via CAN communication can be determined from the combination of CAN communication DTCs that are output. When an open circuit malfunction is confirmed, before disconnecting the connectors for inspection, check whether the connectors are loose by pushing in the connector case. When a connector is disconnected, check if the connector terminals or case is damaged, deformed, deteriorated, etc. VEHICLE BROUGHT TO WORKSHOP NEXT: Go to next step INSPECT BATTERY VOLTAGE Standard voltage 11 to 14 V If the voltage is below 11 V, recharge or replace the battery before proceeding. NEXT: Go to next step CHECK FOR DTC* Using the Techstream, check for all DTCs. NOTE: If codes indicating internal or power source-related malfunctions of ECUs or sensors are output together with codes indicating that those ECUs or sensors cannot communicate via CAN communication, it is likely that the problem is not in the CAN communication line. Therefore, perform troubleshooting for the DTCs related to the malfunctioning parts first. If a connector of a system which includes a CAN communication line is disconnected when the ignition switch is ON or ACC, CAN communication DTCs will be stored by that system and any related systems. NEXT: Go to next step CHECK INSTALLED SYSTEMS (ECU AND SENSOR) THAT USE CAN COMMUNICATION Based on the vehicle equipment and specifications, confirm the systems that use CAN communication. Refer to «DIAGNOSIS SYSTEM [05/2013 - 01/2014]»(ref-615285-S11042255172014050900000). NEXT: Go to next step CHECK FOR OPEN CIRCUIT IN DLC3 CAN BRANCH WIRE AND V1 BUS CIRCUIT CAN MAIN WIRE AND CHECK FOR SHORT CIRCUIT (CANH - CANL) Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the CAN main wire and CAN branch wire. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Switch Condition Specified Condition Proceed to C13-6 (CANH) - C13-14 (CANL) Ignition switch off OK (54 to 69 ohms) A C13-6 (CANH) - C13-14 (CANL) Ignition switch off NG (Higher than 70 ohms) B C13-6 (CANH) - C13-14 (CANL) Ignition switch off NG (Below 53 ohms) C TEXT IN ILLUSTRATION *a Front view of DLC3 B --> Go to "Open in CAN Main Wire". Refer to «Open in CAN Main Wire»(ref-615317-S09492136432014050900000) C --> Go to "Short in CAN Bus Lines". Refer to «Short in CAN Bus Lines»(ref-615317-S39170524232014050900000) A: Go to next step CHECK FOR SHORT TO B+ IN CAN V1 BUS (CANH, CANL - BAT) Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Switch Condition Specified Condition C13-6 (CANH) - C13-16 (BAT) Ignition switch off 6 kohms or higher C13-14 (CANL) - C13-16 (BAT) Ignition switch off 6 kohms or higher TEXT IN ILLUSTRATION *a Front view of DLC3 NG --> Go to "Short to B+ in CAN Bus Line". Refer to «Short to B+ in CAN Bus Line»(ref-615317-S24385451772014050900000) OK: Go to next step CHECK FOR SHORT TO GND IN CAN V1 BUS (CANH, CANL - CG) Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Switch Condition Specified Condition C13-6 (CANH) - C13-4 (CG) Ignition switch off 200 ohms or higher C13-14 (CANL) - C13-4 (CG) Ignition switch off 200 ohms or higher TEXT IN ILLUSTRATION *a Front view of DLC3 NG --> Go to "Short to GND in CAN Bus Line". Refer to «Short to GND in CAN Bus Line»(ref-615317-S39462926022014050900000) OK: Go to next step CHECK ECUS CONNECTED TO CAN BUS* Connect the cable to the negative (-) battery terminal. NOTE: When disconnecting the cable, some systems need to be initialized after the cable is reconnected. Refer to «INITIALIZATION [05/2013 - 01/2014]»(ref-615109-S22240423792014050900000). Select "Bus Check" from "System Select". Refer to «DIAGNOSIS SYSTEM [05/2013 - 01/2014]»(ref-615285-S11042255172014050900000). Check the display of the connected ECUs and sensors for a minute. RESULT Result Proceed to All ECUs and sensors connected to CAN communication system displayed on screen (CAN bus circuit currently normal) A No ECUs connected to power management bus are displayed (power management bus circuit is open) B Single ECU or sensor that should be connected to CAN communication is not displayed (ECU or sensor CAN branch wire open or communication stop) C ECU or sensor that should be connected to CAN communication is not displayed or display is intermittent during check (ECU or sensor CAN branch wire open on one side) D NOTE: ECUs and sensors that are not present will not be displayed. Be careful not to mistake them for communication stop malfunctions. HINT: If the display of an ECU is intermittent during the check, one side of an ECU or sensor CAN branch wire is open (the signal of the ECU is treated as noise, which affects the response and display of the Techstream). The power source control ECU checks for proper ECU communication for ECUs that are connected to the power management bus and the results are displayed on the Techstream. ECUs that stop communicating with the power source control ECU for 3 seconds or more will stop being displayed on the Techstream. B --> Go to "Power Source Control ECU Communication Stop Mode". Refer to «Power Source Control ECU Communication Stop Mode»(ref-615317-S16031123052014050900000) C --> Go to "PROBLEM SYMPTOMS TABLE". Refer to «PROBLEM SYMPTOMS TABLE [05/2013 - 01/2014]»(ref-615285-S17580503522014050900000) D --> Go to "Open in One Side of CAN Branch Line". Refer to «Open in One Side of CAN Branch Line»(ref-615317-S23358423052014050900000) A: Go to next step CHECK COMMUNICATION MALFUNCTION DTC (PAST DTC CHECK)* Select "Bus Check" from "System Select". Refer to «DIAGNOSIS SYSTEM [05/2013 - 01/2014]»(ref-615285-S11042255172014050900000). Write down all of the DTCs stored in each ECU. HINT: If there are communication malfunction DTCs output but the Techstream "Bus Check - Communication Bus Check" screen displays all of the ECUs and sensors connected to the CAN system, the communication malfunction DTCs may be past malfunctions that are no longer present. For V1 bus CAN main wire malfunctions, DTCs for related ECUs are also output. Therefore, determine the malfunctioning area based on all of the DTCs that are output. For power management bus malfunctions, DTCs are stored based on the detection of communication stop malfunctions and network malfunctions of ECUs that are connected by the power source control ECU. RESULT Result Proceed to ECU connected to V1 bus outputs communication trouble code A Power source control ECU (Power Source Control) outputs trouble code other than network malfunction trouble code (past malfunction of ECU or CAN branch wire connected to power management bus) B B --> Go to "DIAGNOSTIC TROUBLE CODE CHART". Refer to «DIAGNOSTIC TROUBLE CODE CHART [05/2013 - 01/2014]»(ref-615285-S18339520122014050900000) A: Go to next step CHECK DTC COMBINATION TABLE (V1 BUS CAN BRANCH WIRE OPEN, PAST COMMUNICATION STOP MALFUNCTION) Based on the combination of output CAN communication system DTCs, determine which ECUs and sensors have a communication stop malfunction. Refer to «DIAGNOSIS SYSTEM [05/2013 - 01/2014]»(ref-615285-S11042255172014050900000). NEXT: Go to next step PERFORM MALFUNCTION SIMULATION TEST (V1 BUS CIRCUIT CAN MAIN WIRE PAST MALFUNCTION)* Using the Techstream, clear all DTCs. Perform a malfunction simulation test on all harnesses and connectors related to the V1 bus CAN main wire. Check the DTCs that were output as a result of the malfunction simulation test. Then determine the malfunctioning area. NEXT: Go to next step ADJUST, REPAIR AND REPLACE NEXT: Go to next step CLEAR DTC* Using the Techstream, clear all DTCs. NEXT: Go to next step CONFIRMATION TEST NEXT --> END

See also:
• DTC U0101: Lost Communication with TCM