CAN Communication System (Diagnostics - Introduction): Overview Toyota 4Runner V

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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 information. Expression Ignition Switch (position) Engine Switch (condition) Ignition Switch off Off Off Ignition Switch ON ON On (IG) Ignition Switch ACC ACC On (ACC) Engine Start START 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 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-422176-S35314398812011092600000) .
4. BUS LINE REPAIR After repairing the bus line with solder, wrap the repaired part with vinyl tape. Refer to «ELECTRONIC CIRCUIT INSPECTION PROCEDURE»(ref-421949-S41663372572011092600000) . NOTE: The CANL bus line and CANH bus line must be installed together. When installing the CAN bus lines, be 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 protective effect of the twisted wire harness is 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

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W/ SMART KEY SYSTEM

1. *1: w/ Navigation System
2. *2: for 4WD

W/O SMART KEY SYSTEM

1. *1: w/ Navigation System
2. *2: for 4WD
3. *3: w/ Kinetic Dynamic Suspension System
4. *4: w/ CRAWL Control

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1. w/ Smart Key System
2. w/o Smart Key System

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 using 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 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*1 and MS bus*2 each have termination circuits with a resistance of 120 ohms x 2. High speed communication at 500 kbps and 250 kbps is possible. *1: w/ Smart Key System *2: w/ CRAWL Control
4. ECUS OR SENSORS WHICH COMMUNICATE VIA CAN COMMUNICATION SYSTEM Combination meter assembly Master cylinder solenoid (skid control ECU) Main body ECU (multiplex network body ECU) Stabilizer control ECU*1 Center airbag sensor assembly Spiral cable sub-assembly (steering angle sensor) DLC3 Navigation receiver assembly*2 Certification ECU*3 Yaw rate sensor assembly Power steering ECU assembly Four wheel drive control ECU*4 Air conditioning amplifier assembly Power management control ECU*3 Drive monitor switch*5 ECM *1: w/ Kinetic Dynamic Suspension System *2: w/ Navigation System *3: w/ Smart Key System *4: for 4WD *5: w/ CRAWL Control
5. DIAGNOSTIC CODES FOR CAN COMMUNICATION SYSTEM DTCs for the CAN communication system are as follows: U0073, U0100, U0101, U0114, U0122, U0123, U0124, U0126, U0129, U0131, U0139, U0140, U0142, U0151, U0155, U0164, U0327, U1002, U1133 and U1114.
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 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: Refer to "Terminals of ECU". Refer to «TERMINALS OF ECU»(ref-422172-S01969904972011092600000) for bus line color or the connecting side of the connector.

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1. IMPORTANT POINTS CONCERNING TROUBLESHOOTING WARNING: Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS 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»(ref-421949-S36027747902011092600000) . 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 branch line or V1 bus main line for malfunctions by inspecting the terminals of the DLC3 using SST. NOTE: It is only possible to inspect branch lines 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 "CAN Bus Check" function of the Techstream (when the DLC3 branch wire and V1 bus main wire are normal). HINT: When checking "CAN Bus Check", ECUs (sensors) whose branch line is open or that CANnot communicate via CAN communication do not respond to the Techstream (they are not displayed on the screen). When checking "CAN 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 management control ECU detects malfunctions in the power management bus circuit and stores 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. The main body ECU (multiplex network body ECU) detects malfunctions in the MS bus circuit and stores 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 AND CLEAR DTC* Using the Techstream, perform the Health Check (all DTCs check). 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 are 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»(ref-422172-S12776609432011092600000) . NEXT: Go to next step CHECK FOR OPEN CIRCUIT IN DLC3 BRANCH WIRE AND V1 BUS CIRCUIT MAIN WIRE AND SHORT CIRCUIT (CANH - CANL) Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the main wire and branch wire. Measure the resistance of the DLC3. Standard Resistance Tester Connection Switch Condition Specified Condition Proceed to F13-6 (CANH) - F13-14 (CANL) Ignition switch off OK (54 to 69 ohms) A F13-6 (CANH) - F13-14 (CANL) Ignition switch off NG (Higher than 69 ohms) B F13-6 (CANH) - F13-14 (CANL) Ignition switch off NG (Below 54 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-422235-S26769881152011092600000) C --> Go to "Short in CAN Bus Lines". Refer to «Short in CAN Bus Lines»(ref-422235-S39479258842011092600000) A: Go to next step CHECK FOR SHORT TO +B IN CAN V1 BUS (CANH, CANL - BAT) Measure the resistance of the DLC3. Standard Resistance Tester Connection Switch Condition Specified Condition F13-6 (CANH) - F13-16 (BAT) Ignition switch off 6 kohms or higher F13-14 (CANL) - F13-16 (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 Lines". Refer to «Short to B+ in CAN Bus Line»(ref-422235-S15470185632011092600000) OK: Go to next step CHECK FOR SHORT TO GND IN CAN V1 BUS (CANH, CANL - CG) Measure the resistance of the DLC3. Standard Resistance Tester Connection Switch Condition Specified Condition F13-6 (CANH) - F13-4 (CG) Ignition switch off 200 ohms or higher F13-14 (CANL) - F13-4 (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 Lines". Refer to «Short to GND in CAN Bus Line»(ref-422235-S08713384712011092600000) 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»(ref-421949-S36027747902011092600000) . Select "CAN Bus Check" from the screen on the Techstream. Refer to «DIAGNOSIS SYSTEM»(ref-422172-S12776609432011092600000) . Check the display of the connected ECUs and sensors for a minute. RESULT Inspection Result Proceed to All ECUs and sensors connected to CAN communication system displayed on screen (CAN bus circuit currently normal) A w/ Smart Key System: Except for power management control ECU (Power Management1), no ECUs connected to power management bus are displayed (power management bus main wire open or short malfunction) B w/ Smart Key System: No ECUs connected to power management bus are displayed (the power management bus circuit is open) C w/o Smart Key System: Except for main body ECU (multiplex network body ECU), no ECUs connected to MS bus are displayed (MS bus main wire open or short malfunction) D w/o Smart Key System: No ECUs connected to MS bus are displayed (branch wire between main body ECU (multiplex network body ECU) and MS bus circuit is open) E Only one ECU or sensor that should be connected to CAN communication is not displayed (ECU or sensor branch wire open or communication stop) F ECU or sensor that should be connected to CAN communication is not displayed or display is intermittent during check (ECU or sensor branch wire open on one side) G NOTE: ECUs and sensors that are not present are not 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 branch wire is open (the signal of the ECU is treated as noise, which affects the response and display of the Techstream). w/ Smart Key System: The power management 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 management control ECU for 3 seconds or more stop being displayed on the Techstream. The power management control ECU (Power Management1) may be malfunctioning if both of the following occur: 1) all ECUs connected to the power management bus are not displayed on the Techstream; and 2) DTC U1002 Lost Communication with Gateway Module (Power Management Bus) is not output. w/o Smart Key System: The main body ECU (multiplex network body ECU) checks for proper ECU communication for ECUs that are connected to the MS bus and the results are displayed on the Techstream. ECUs that stop communicating with the main body ECU for 3 seconds or more stop being displayed on the Techstream. The main body ECU (multiplex network body ECU) may be malfunctioning if both of the following occur: 1) all ECUs connected to the power management bus are not displayed on the Techstream; and 2) DTC U1002 Lost Communication with Gateway Module (MS Bus) is not output. B --> Go to "DTC U1002". Refer to «DTC U1002: Lost Communication with Gateway Module (Power Management2)»(ref-422235-S28058596032011092600000) C --> Go to "Power Management Control ECU Communication Stop Mode". Refer to «Power Management Control ECU Communication Stop Mode»(ref-422235-S30585996892011092600000) D --> Go to "DTC U1002". Refer to «DTC U1002: Lost Communication with Gateway Module (MS Bus); DTC U1114: Lost Communication with Main Switch Module»(ref-422235-S22566747232011092600000) E --> Go to "Main Body ECU Communication Stop Mode". Refer to «Main Body ECU Communication Stop Mode»(ref-422235-S12709405572011092600000) F --> Go to "PROBLEM SYMPTOMS TABLE". Refer to «PROBLEM SYMPTOMS TABLE»(ref-422172-S35869893572011092600000) G --> Go to "Open in One Side of CAN Branch Wire". Refer to «Open in One Side of CAN Branch Line»(ref-422235-S12502745882011092600000) A: Go to next step CHECK COMMUNICATION MALFUNCTION DTC (PAST DTC CHECK)* Select "CAN Bus Check" from the screen on the Techstream. Refer to «DIAGNOSIS SYSTEM»(ref-422172-S12776609432011092600000) . Write down all of the DTCs output from 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 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 MS bus malfunctions, DTCs are stored based on the detection of communication stop malfunctions and network malfunctions of ECUs that are connected by the main body ECU. 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 management control ECU. RESULT Inspection Result Proceed to ECU connected to V1 bus outputs communication trouble code A w/ Smart Key System: Power management control ECU (Power Management1) outputs network malfunction trouble code (U1002) (power management bus main wire past malfunction) B w/ Smart Key System: Power management control ECU (Power Management1) outputs trouble code other than network malfunction trouble code (U1002) (past malfunction of ECU or branch wire connected to power management bus) C w/o Smart Key System: Main body ECU (multiplex network body ECU) outputs network malfunction trouble code (U1002) (MS bus main wire past malfunction) D w/o Smart Key System: Main body ECU (multiplex network body ECU) outputs trouble code other than network malfunction trouble code (U1002) (past malfunction of ECU or branch wire connected to MS bus) E B --> Go to "DTC U1002". Refer to «DTC U1002: Lost Communication with Gateway Module (Power Management2)»(ref-422235-S28058596032011092600000) C --> Go to "DIAGNOSTIC TROUBLE CODE CHART". Refer to «DIAGNOSTIC TROUBLE CODE CHART»(ref-422172-S11395652362011092600000) D --> Go to "DTC U1002". Refer to «DTC U1002: Lost Communication with Gateway Module (MS Bus); DTC U1114: Lost Communication with Main Switch Module»(ref-422235-S22566747232011092600000) E --> Go to "DIAGNOSTIC TROUBLE CODE CHART". Refer to «DIAGNOSTIC TROUBLE CODE CHART»(ref-422172-S11395652362011092600000) A: Go to next step CHECK DTC COMBINATION TABLE (V1 BUS 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»(ref-422172-S12776609432011092600000) . NEXT: Go to next step PERFORM MALFUNCTION SIMULATION TEST (V1 BUS CIRCUIT 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 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