SYSTEM DESCRIPTION 1. 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. 2. DEFINITION OF TERMS (a) Central bus (1) The central bus is a generic name for multiple subordinate CAN bus lines on 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:
(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. NOTICE: Gateway function not equipped ECU is a generic name for ECUs not connected to the central gateway ECU (network gateway ECU) with a gateway function. (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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Toyota Tundra Service Manual > Engine Immobiliser System (w/o Smart Key System): Precaution
PRECAUTION PRECAUTIONS WHEN USING TECHSTREAM (a) After all DTCs are cleared, check if the malfunction occurs again 6 seconds after turning the ignition switch to ON. PRECAUTIONS FOR THE KEY (a) The key is a precision instrument. Be sure to observe the following: (1) Do not drop or strike the key. (2 ...