DESCRIPTION When the CAN bus main lines are normal (no open, short to ground, short to +B or short between lines) and there is an ECU or sensor on the "Communication Bus Check" screen that is indicated as not communicating or whose connection status on the "Communication Bus Check" screen changes intermittently, an open in one of the wires of a CAN bus branch line is suspected. HINT: If there is an ECU or sensor whose connection status changes intermittently while checking the "Communication Bus Check" screen, there may be an open circuit in one of the wires of a branch line of an ECU or sensor in the bus. If an open occurs in one of the wires of a CAN branch line, it may interfere with the communication of other ECUs or sensors resulting in an incorrect state being displayed.
CAUTION / NOTICE / HINT CAUTION: When performing the confirmation driving pattern, obey all speed limits and traffic laws. NOTICE:
PROCEDURE
(a) Based on the vehicle equipment and specifications, confirm the systems that use CAN communication. Click here (b) Connect the Techstream to the DLC3. (c) Turn the ignition switch to ON. (d) Turn the Techstream on. (e) Using the Techstream, perform "CAN Bus Check". Click here
(f) Observe the screen for approximately 2 minutes to check for ECUs and sensors that are displayed as not communicating. (g) Perform the inspection as specified in the Problem Symptoms Table for the ECUs or sensors that are not communicating.
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Toyota Tundra Service Manual > Audio And Visual System: Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter
DESCRIPTION Audio function: This circuit is necessary for the automatic sound levelizer (ASL) built into the radio and display receiver assembly. ASL function: Speed signals are received from the combination meter assembly and used for the ASL. The ASL function automatically adjusts the sound volume ...