- CAN main bus line or connector
- Central gateway ECU (network gateway ECU)
- Hybrid vehicle control ECU
- No. 4 CAN junction connector
- No. 7 CAN junction connector
Lexus NX: Open in Bus 5 Main Bus Line
Lexus NX Service Manual / Power Source & Network / Networking / Can Communication System / Open in Bus 5 Main Bus Line
DESCRIPTION
There may be an open circuit in one of the CAN main bus lines when the resistance between terminals 15 (CA5H) and 16 (CA5L) of the central gateway ECU (network gateway ECU) is 70 Ω or higher.
| Symptom | Trouble Area |
|---|---|
| Resistance between terminals 15 (CA5H) and 16 (CA5L) of central gateway ECU (network gateway ECU) is 70 Ω or higher. | |
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. 4 CAN JUNCTION CONNECTOR) |
(a) Disconnect the cable from the negative (-) auxiliary battery terminal.
| (b) Disconnect the No. 4 CAN junction connector. |
|
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition | Connected to |
|---|---|---|---|
| I95-3 (CANH) - I95-13 (CANL) | Cable disconnected from negative (-) auxiliary battery terminal | 108 to 132 Ω | Central gateway ECU (network gateway ECU) |
| I95-9 (CANH) - I95-19 (CANL) | Cable disconnected from negative (-) auxiliary battery terminal | 108 to 132 Ω | No. 7 CAN junction connector |
| Result | Proceed to |
|---|---|
| OK | A |
| NG (No. 7 CAN junction connector CAN main wire) | B |
| NG (Central gateway ECU [network gateway ECU] CAN main wire) | C |
| A | .gif) | REPLACE NO. 4 CAN JUNCTION CONNECTOR |
| C | | GO TO STEP 6 |
|
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| 2. | CONNECT CONNECTOR |
(a) Reconnect the I95 No. 4 CAN junction connector.
|
| 3. | CHECK FOR OPEN IN CAN BUS WIRE (NO. 8 CAN JUNCTION CONNECTOR) |
| (a) Disconnect the No. 7 CAN junction connector. |
|
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition | Connected to |
|---|---|---|---|
| Q32-4 (CANH) - Q32-14 (CANL) | Cable disconnected from negative (-) auxiliary battery terminal | 108 to 132 Ω | Hybrid vehicle control ECU |
| Q32-5 (CANH) - Q32-15 (CANL) | Cable disconnected from negative (-) auxiliary battery terminal | 108 to 132 Ω | No. 4 CAN junction connector |
| Result | Proceed to |
|---|---|
| OK | A |
| NG (Hybrid vehicle control ECU CAN main wire) | B |
| NG (No. 4 CAN junction connector CAN main wire) | C |
| A | | REPLACE NO. 8 CAN JUNCTION CONNECTOR |
| C | | REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (NO. 7 CAN JUNCTION CONNECTOR - NO. 4 CAN JUNCTION CONNECTOR) |
|
| 4. | CONNECT CONNECTOR |
(a) Reconnect the Q32 No. 8 CAN junction connector.
|
| 5. | CHECK FOR OPEN IN CAN BUS WIRE (HYBRID VEHICLE CONTROL ECU - NO. 7 CAN JUNCTION CONNECTOR) |
| (a) Disconnect the hybrid vehicle control ECU connector. |
|
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| I115-34(CA2H) - I115-35(CA2L) | Cable disconnected from negative (-) auxiliary battery terminal | 108 to 132 Ω |
| OK | | REPLACE HYBRID VEHICLE CONTROL ECU |
| NG | | REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (HYBRID VEHICLE CONTROL ECU - NO. 8 CAN JUNCTION CONNECTOR) |
| 6. | CONNECT CONNECTOR |
(a) Reconnect the I95 No. 4 CAN junction connector.
|
| 7. | CHECK FOR OPEN IN CAN BUS WIRE (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU] - NO. 4 CAN JUNCTION CONNECTOR) |
| (a) Disconnect the central gateway ECU (network gateway ECU) connector. |
|
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| I160-15(CA5H) - I160-16(CA5L) | Cable disconnected from negative (-) auxiliary battery terminal | 108 to 132 Ω |
| OK | | REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) |
| NG | | REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU] - NO. 4 CAN JUNCTION CONNECTOR) |
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