Toyota Yaris: Can Communication System / System Description
SYSTEM DESCRIPTION
BRIEF DESCRIPTION
(a) The Controller Area Network (CAN) is a serial data communication system for real time application. It is a vehicle multiplex communication system which has a high communication speed and the ability to detect malfunctions.
(b) Using the CANH and CANL bus lines as a pair, CAN communication is performed using a voltage differential. (A base voltage is applied to the pair of lines and a voltage differential is created when communicating.)
(c) Many ECUs or sensors installed to the vehicle operate by sharing information and communicating with each other.
(d) 2 resistors which are necessary for communication are used in a CAN bus main line.
DEFINITION OF TERMS
(a) Central bus
(1) The central bus is a term used to describe all buses directly connected to the central gateway ECU (network gateway ECU).
HINT:
A bus is displayed as Bus on the "Communication Bus Check" screen of the GTS.
(b) Sub bus
(1) A sub bus is a bus that has a gateway function equipped ECU in order to communicate with the central bus and other sub buses.
HINT:
-
A sub bus is displayed as Sub bus on the "Communication Bus Check" screen of the GTS.
-
When Sub bus is selected on the "Communication Bus Check" screen, ECUs and sensors connected to non-CAN networks such as LIN may also be displayed in addition to the ECUs and sensors connected to sub buses in the CAN network.
(c) Local bus
(1) A local bus is a bus that does not have the ability to communicate with other buses. ECUs and sensors on a local bus can only communicate with other ECUs and sensors on the same bus.
(d) CAN J/C
(1) A CAN junction connector is a connector that connects branch lines to a main bus.
(e) Main bus
(1) A main bus line is the wire harness that runs between the 2 terminating resistors of a bus.
(f) Branch
(1) A branch line is a wire harness that connects an ECU or sensor to a main bus line.
(g) Terminating resistors
(1) Terminating resistors which maintain a stable signal inside the CAN bus are installed. 2 resistors of 120 Ω each located at each end of the bus are necessary.
SYSTEM DIAGRAM (a) The CAN communication system is composed of 8 buses.
CAN Main Bus Line
Terminating Resistor
CAN Branch Line * Gateway Function Equipped ECU
Bus Monitoring Direction - - Connected to Code ECU/Sensor Name GTS Display Applicability - CGW Central Gateway ECU (Network Gateway ECU) - Installed on all vehicles - DLC3 DLC3 - Installed on all vehicles Bus 1 F-CAM Forward Recognition Camera Front Camera Module w/ Toyota Safety Sense F-MR Millimeter Wave Radar Sensor Assembly Front Radar w/ Toyota Safety Sense CAN Global J/C NO...
CAUTION / NOTICE / HINT NOTICE:
Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output...
Other information:
ComponentsCOMPONENTS ILLUSTRATION
*1 NEUTRAL POSITION SWITCH *2 GASKET *3 NO. 1 ENGINE UNDER COVER ASSEMBLY *4 ENGINE UNDER COVER LH
N*m (kgf*cm, ft.*lbf): Specified torque ● Non-reusable part RemovalREMOVAL PROCEDURE 1...
DESCRIPTION Problem Symptom Suspected Area Trouble Area
Engine speed fluctuation due to abnormal combustion
Idle speed too low or high
Strong engine vibration due to above symptoms
Ignition malfunction
Deviation in air fuel ratio (Excessive or insufficient intake air volume or fuel supply)
Insufficient compression
Changes in load from another system
Ignition system
Spark plug
Ignition coil assembly
Fuel system
Direct fuel injector assembly
Port fuel injector assembly
Fuel pump assembly (for high pressure side)
Fuel pump (for low pressure side)
Fuel pump control circuit
Fuel suction plate sub-assembly
Fuel main valve assembly
Fuel line
Purge VSV system
Fuel quality (existence of foreign matter, degradation)
Intake and exhaust systems
Mass air flow meter sub-assembly
Intake system
(Air leaks or deposit accumulation)
Throttle body with motor assembly
Air fuel ratio sensor (sensor 1)
Air fuel ratio sensor (sensor 2)
Cam timing oil control solenoid assembly
Variable Valve Timing system (VVT system)
Other control systems
ECM
Wire harness or connector
Knock control sensor
Engine coolant temperature sensor
Engine
Water control valve
Engine assembly
High load from another system
Air conditioning system
Power steering system
Electrical load signal system
SYMPTOM AND CAUSE OF SYSTEM MALFUNCTION HINT: The following are descriptions of the characteristics of each system malfunction...