Lexus ES: 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 Techstream.
(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 Techstream.
- 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.
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System Diagram
SYSTEM DIAGRAM (a) The CAN communication system is composed of 5 buses. CAN Main Bus Line Terminating Resistor CAN Branch Line * Gateway Function Equipped ECU Bus Monitor
Parts Location
PARTS LOCATION ILLUSTRATION *1 SWING GRILLE ACTUATOR ASSEMBLY *2 MILLIMETER WAVE RADAR SENSOR ASSEMBLY *3 HEADLIGHT ECU SUB-ASSEMBLY RH *4 INVERTER WITH CONVERTER ASSEMBLY *5
Precaution
PRECAUTION NOTICE FOR INITIALIZATION NOTICE: When disconnecting the cable from the negative (-) auxiliary battery terminal, initialize the following systems after the cable is reconnected. System
SEE MORE:
Relay
On-vehicle InspectionON-VEHICLE INSPECTION PROCEDURE 1. INSPECT IGCT RELAY (IGCT) (a) Measure the resistance according to the value(s) in the table below. Standard Resistance: Tester Connection Condition Specified Condition 3 - 5 Auxiliary battery voltage not applied between termin
Data List / Active Test
DATA LIST / ACTIVE TEST DATA LIST NOTICE: In the table below, the values listed under "Normal Condition" are reference values. Do not depend solely on these reference values when deciding whether a part is faulty or not. HINT: Using the Techstream to read the Data List allows the values or states of
