- Resistance between terminals 6 (CA3H) and 21 (CA3L) of the central gateway ECU (network gateway ECU) is 70 Ω or higher.
- Resistance between terminals 19 (CAYH) and 20 (CAYL) of the central gateway ECU (network gateway ECU) is 70 Ω or higher.
Lexus NX: Open in Bus 3 Main Bus Line
Lexus NX Service Manual / Power Source & Network / Networking / Can Communication System / Open in Bus 3 Main Bus Line
DESCRIPTION
There may be an open circuit in one of the CAN main bus lines when the resistance between terminals 6 (CA3H) and 21 (CA3L) of the central gateway ECU (network gateway ECU) is 70 Ω or higher.
| Symptom | Trouble Area |
|---|---|
| |
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This malfunction is not related to the lines of a CAN branch or to ECUs or sensors connected to a CAN branch.
WIRING DIAGRAM
CAUTION / NOTICE / HINT
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
NOTICE:
- Inspect the fuses for circuits related to this system before performing the following procedure.
- Before measuring the resistance of the CAN bus, turn the power switch off and leave the vehicle for 1 minute or more without operating the key or any switches, or opening or closing the doors. After that, disconnect the cable from the negative (-) auxiliary battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
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After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal.
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When disconnecting and reconnecting the auxiliary battery.
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HINT:
When disconnecting and reconnecting the auxiliary battery, there is an automatic learning function that completes learning when the respective system is used.
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Some parts must be initialized and set when replacing or removing and installing parts.
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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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HINT:
- Operating the power switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.
- Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.
PROCEDURE
| 1. | CHECK FOR OPEN IN CAN BUS WIRE (NO. 10 CAN JUNCTION CONNECTOR) |
(a) Disconnect the cable from the negative (-) auxiliary battery terminal.
| (b) Disconnect the No. 10 CAN junction connector. |
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(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition | Connected to |
|---|---|---|---|
| I164-1 (CANH) - I164-12 (CANL) | Cable disconnected from negative (-) auxiliary battery terminal | 108 to 132 Ω | Central gateway ECU (network gateway ECU) |
| I164-5 (CANH) - I164-16 (CANL) | Cable disconnected from negative (-) auxiliary battery terminal | 108 to 132 Ω | Central gateway ECU (network gateway ECU) |
| OK | .gif) | REPLACE NO. 10 CAN JUNCTION CONNECTOR |
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| 2. | CHECK FOR OPEN IN CAN BUS WIRE (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU] - NO. 10 CAN JUNCTION CONNECTOR) |
| (a) Measure the resistance according to the value(s) in the table below. Standard Resistance:
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| OK | | REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU] - NO. 10 CAN JUNCTION CONNECTOR) |
| NG | | REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) |
READ NEXT:
Check Bus 3 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 6 (CA3H) and 21 (CA3L) of the central gateway ECU (network gateway
Check Bus 3 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 6 (CA3H) of the central gateway ECU (network gateway ECU) and terminal 16
Open in One Side of Bus 3 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 indicate
SEE MORE:
Problem Symptoms Table
PROBLEM SYMPTOMS TABLE NOTICE: If the main body ECU (multiplex network body ECU) is replaced, refer to the Smart Access System with Push-button Start (for Entry Function). Click here HINT:
Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are list
Shut Down Signal Circuit
DESCRIPTION The cause of the malfunction may be a shutdown signal. Check whether there is a shutdown signal +B short circuit. Related Parts Check Area Inspection Step HSDN terminal voltage Check that the HSDN terminal voltage decreases while READY OFF (IG ON). If the voltage is low, the
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