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Communication stop for "Power Steering (EPS)" is indicated on "Communication Bus Check".
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Communication system DTCs (DTCs that start with U) that are output correspond to "Power Steering ECU Communication Stop Mode" in "DTC Combination Table".
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Lexus NX: Power Steering ECU Communication Stop Mode
Lexus NX Service Manual / Power Source & Network / Networking / Can Communication System / Power Steering ECU Communication Stop Mode
DESCRIPTION
| Detection Item | Symptoms | Trouble Area |
|---|---|---|
| Power Steering ECU Communication Stop Mode | Any of the following conditions are met: |
|
WIRING DIAGRAM
for Power Tilt and Power Telescopic Steering Column:
for Manual Tilt and Manual Telescopic Steering Column: 
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 inspection 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, 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 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 VEHICLE TYPE |
(a) Check vehicle type.
| Result | Proceed to |
|---|---|
| for Power Tilt and Power Telescopic Steering Column | A |
| for Manual Tilt and Manual Telescopic Steering Column | B |
| B | .gif) | GO TO STEP 7 |
|
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| 2. | CHECK FOR OPEN IN CAN BUS WIRE (POWER STEERING ECU ASSEMBLY BRANCH WIRE) |
(a) Disconnect the cable from the negative (-) auxiliary battery terminal.
| (b) Disconnect the power steering ECU assembly connector. |
|
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| n2-7 (CANH) - n2-8 (CANL) | Cable disconnected from negative (-) auxiliary battery terminal | 54 to 69 Ω |
| NG | | GO TO STEP 6 |
|
| 3. | CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT) |
| (a) Reconnect the cable to the negative (-) auxiliary battery terminal. |
|
(b) Disconnect the ECU wire sub-assembly connector.
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Switch Condition | Specified Condition |
|---|---|---|
| An1-1 (PIG) - Body ground | Power switch off | 9 to 16 V |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT) |
|
| 4. | CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT) |
| (a) Disconnect the ECU wire sub-assembly connector. |
|
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Switch Condition | Specified Condition |
|---|---|---|
| nl1-5 (IG) - Body ground | Power switch on (IG) | 11 to 14 V |
| Power switch off | Below 1 V |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT) |
|
| 5. | CHECK ECU WIRE SUB-ASSEMBLY |
(a) Reconnect the ECU wire sub-assembly connectors.
| (b) Disconnect the power steering ECU assembly connectors. |
|
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Switch Condition | Specified Condition |
|---|---|---|
| n2-1 (IG) - Body ground | Power switch on (IG) | 8 to 16 V |
| Power switch off | Below 1 V | |
| n1-1 (PIG) - Body ground | Power switch off | 9 to 16 V |
(d) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| n1-2 (PGND) - Body ground | Always | Below 1 Ω |
| OK | | REPLACE POWER STEERING ECU ASSEMBLY |
| NG | | REPLACE ECU WIRE SUB-ASSEMBLY |
| 6. | CHECK FOR OPEN IN CAN BRANCH WIRE |
| (a) Disconnect the ECU wire sub-assembly connector. |
|
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| nl1-1 (CANH) - nl1-2 (CANL) | Cable disconnected from negative (-) auxiliary battery terminal | 54 to 69 Ω |
| OK | | REPLACE ECU WIRE SUB-ASSEMBLY |
| NG | | REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR |
| 7. | CHECK FOR OPEN IN CAN BUS WIRE (POWER STEERING ECU ASSEMBLY BRANCH WIRE) |
(a) Disconnect the cable from the negative (-) auxiliary battery terminal.
| (b) Disconnect the power steering ECU assembly connector. |
|
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| n3-4 (CANH) - n3-8 (CANL) | Cable disconnected from negative (-) auxiliary battery terminal | 54 to 69 Ω |
| NG | | GO TO STEP 11 |
|
| 8. | CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT) |
| (a) Reconnect the cable to the negative (-) auxiliary battery terminal. |
|
(b) Disconnect the ECU wire sub-assembly connector.
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Switch Condition | Specified Condition |
|---|---|---|
| An1-1 (PIG) - Body ground | Power switch off | 9 to 16 V |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT) |
|
| 9. | CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT) |
| (a) Disconnect the ECU wire sub-assembly connector. |
|
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Switch Condition | Specified Condition |
|---|---|---|
| nl1-5 (IG) - Body ground | Power switch on (IG) | 11 to 14 V |
| Power switch off | Below 1 V |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT) |
|
| 10. | CHECK ECU WIRE SUB-ASSEMBLY |
(a) Reconnect the ECU wire sub-assembly connectors.
| (b) Disconnect the power steering ECU assembly connectors. |
|
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Switch Condition | Specified Condition |
|---|---|---|
| n3-1 (IG) - Body ground | Power switch on (IG) | 8 to 16 V |
| Power switch off | Below 1 V | |
| n1-1 (PIG) - Body ground | Power switch off | 9 to 16 V |
(d) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| n1-2 (PGND) - Body ground | Always | Below 1 Ω |
| OK | | REPLACE POWER STEERING ECU ASSEMBLY |
| NG | | REPLACE ECU WIRE SUB-ASSEMBLY |
| 11. | CHECK FOR OPEN IN CAN BUS WIRE (POWER STEERING ECU ASSEMBLY BRANCH WIRE) |
| (a) Disconnect the ECU wire sub-assembly connector. |
|
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| nl1-1 (CANH) - nl1-2 (CANL) | Cable disconnected from negative (-) auxiliary battery terminal | 54 to 69 Ω |
| OK | | REPLACE ECU WIRE SUB-ASSEMBLY |
| NG | | REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR |
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