- CAN main bus wire or connector
- Central gateway ECU (network gateway ECU) branch wire
- ECM
- Combination meter assembly
- No. 2 CAN junction connector
- No. 3 CAN junction connector
Lexus NX: Open in Bus 2 Main Bus Line
Lexus NX Service Manual / Power Source & Network / Networking / Can Communication System / Open in Bus 2 Main Bus Line
DESCRIPTION
There may be an open circuit in one of the CAN main bus wire and/or a central gateway ECU (network gateway ECU) branch wire when the resistance between terminals 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway ECU) is 70 Ω or higher.
| Symptom | Trouble Area |
|---|---|
| Resistance between terminals 18 (CA4H) and 17 (CA4L) of central gateway ECU (network gateway ECU) is 70 Ω or higher. | |
This malfunction is not related to the lines of a CAN branch except the central gateway ECU (network gateway ECU) branch wire 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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- When replacing the combination meter assembly, always replace it with a new one. If a combination meter assembly which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored
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 (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU] - NO. 2 CAN JUNCTION CONNECTOR) |
(a) Disconnect the cable from the negative (-) auxiliary battery terminal.
| (b) Disconnect the central gateway ECU (network gateway ECU) connector. |
|
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| I160-18 (CA4H) - I160-17 (CA4L) | Cable disconnected from negative (-) auxiliary battery terminal | 108 to 132 Ω |
| NG | .gif) | REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU] - NO. 2 CAN JUNCTION CONNECTOR) |
|
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| 2. | CONNECT CONNECTOR |
(a) Connect the I160 central gateway ECU (network gateway ECU) connector.
|
| 3. | CHECK FOR OPEN IN CAN BUS WIRE (NO. 2 CAN JUNCTION CONNECTOR) |
| (a) Disconnect the No. 2 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 |
|---|---|---|---|
| I93-5 (CANH) - I93-15 (CANL) | Cable disconnected from negative (-) auxiliary battery terminal | 108 to 132 Ω | No. 3 CAN junction connector |
| I93-7 (CANH) - I93-17 (CANL) | Cable disconnected from negative (-) auxiliary battery terminal | 108 to 132 Ω | Combination meter assembly |
| Result | Proceed to |
|---|---|
| OK | A |
| NG (Combination meter assembly CAN main wire) | B |
| NG (No. 3 CAN junction connector CAN main wire) | C |
| A | | REPLACE NO. 2 CAN JUNCTION CONNECTOR |
| C | | GO TO STEP 6 |
|
| 4. | CONNECT CONNECTOR |
(a) Connect the I93 No. 2 CAN junction connector.
|
| 5. | CHECK FOR OPEN IN CAN BUS WIRE (COMBINATION METER ASSEMBLY - NO. 2 CAN JUNCTION CONNECTOR) |
| (a) Disconnect the combination meter assembly connector. |
|
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(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| I10-29 (CANH) - I10-30 (CANL) | Cable disconnected from negative (-) auxiliary battery terminal | 108 to 132 Ω |
| OK | | REPLACE COMBINATION METER ASSEMBLY |
| NG | | REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (COMBINATION METER ASSEMBLY - NO. 2 CAN JUNCTION CONNECTOR) |
| 6. | CONNECT CONNECTOR |
(a) Connect the I93 No. 2 CAN junction connector.
|
| 7. | CHECK FOR OPEN IN CAN BUS WIRE (NO. 3 CAN JUNCTION CONNECTOR) |
| (a) Disconnect the No. 3 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 |
|---|---|---|---|
| I94-6 (CANH) - I94-16 (CANL) | Cable disconnected from negative (-) auxiliary battery terminal | 108 to 132 Ω | No. 2 CAN junction connector |
| I94-7 (CANH) - I94-17 (CANL) | Cable disconnected from negative (-) auxiliary battery terminal | 108 to 132 Ω | ECM |
| Result | Proceed to |
|---|---|
| OK | A |
| NG (ECM CAN main wire) | B |
| NG (No. 2 CAN junction connector main wire) | C |
| A | | REPLACE NO. 3 CAN JUNCTION CONNECTOR |
| C | | REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (NO. 3 CAN JUNCTION CONNECTOR - NO. 2 CAN JUNCTION CONNECTOR) |
|
| 8. | CONNECT CONNECTOR |
(a) Connect the I94 No. 3 CAN junction connector.
|
| 9. | CHECK FOR OPEN IN CAN BUS WIRE (ECM - NO. 3 CAN JUNCTION CONNECTOR) |
| (a) Disconnect the ECM connector. |
|
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| A35-13 (CANH) - A35-26 (CANL) | Cable disconnected from negative (-) auxiliary battery terminal | 108 to 132 Ω |
| OK | | REPLACE ECM |
| NG | | REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (ECM - NO. 3 CAN JUNCTION CONNECTOR) |
READ NEXT:
Check Bus 2 Lines for Short Circuit
DESCRIPTION There may be a short circuit between the CAN main bus wire and/or CAN branch wire when the resistance between terminals 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway
Check Bus 2 Line for Short to +B
DESCRIPTION There may be a short circuit between one of the CAN bus wire and +B when there is no resistance between terminal 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 16
Check Bus 2 Line for Short to GND
DESCRIPTION There may be a short circuit between one of the CAN bus wire and GND when there is no resistance between terminal 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 4
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If the engine is
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