Lexus ES: Open in One Side of Bus 1 Branch Line
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.
| Symptom | Trouble Area |
|---|---|
| There is an ECU or sensor that is indicated as not communicating on the "Communication Bus Check" screen or whose connection status on the "Communication Bus Check" screen changes intermittently. | One side of CAN branch line is open, or output signals are incomplete.
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CAUTION / NOTICE / HINT
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
NOTICE:
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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.
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After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.
DTC check procedure: Turn the power switch on (IG) and wait for 1 minute or more. Then operate the suspected malfunctioning system and drive the vehicle at 60 km/h (37 mph) or more for 5 minutes or more.
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After the repair, perform the CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed as normal.
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PROCEDURE
| 1. | CHECK FOR OPEN IN ONE SIDE OF CAN BRANCH LINE |
(a) Based on the vehicle equipment and specifications, confirm the systems that use CAN communication.
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(b) Connect the Techstream to the DLC3.
(c) Turn the power switch on (IG).
(d) Turn the Techstream on.
(e) Using the Techstream, perform "CAN Bus Check".
CAN Bus Check(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.
| NEXT | .gif) | GO TO CORRESPONDING COMMUNICATION STOP MODE |
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Check Bus 1 Line for Short to GND
DESCRIPTION There may be a short circuit between one of the CAN bus lines and GND when there is no resistance between terminal 23 (CA1H) of the central gateway ECU (network gateway ECU) and terminal 4
Check Bus 1 Line for Short to +B
DESCRIPTION There may be a short circuit between one of the CAN bus lines and +B when there is no resistance between terminal 23 (CA1H) of the central gateway ECU (network gateway ECU) and terminal 16
Check Bus 1 Lines for Short Circuit
DESCRIPTION There may be a short circuit between the CAN main bus lines and/or CAN branch lines when the resistance between terminals 23 (CA1H) and 8 (CA1L) of the central gateway ECU (network gateway
SEE MORE:
How To Proceed With Troubleshooting
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