- Short to GND in CAN main bus wire
- Short to GND in CAN branch wire
- Forward recognition camera*1
- Clearance warning ECU assembly*2
- Millimeter wave radar sensor assembly*1
- Central gateway ECU (network gateway ECU)
- Parking assist ECU*3
- Blind spot monitor sensor LH*4
- Rear television camera assembly
- Hybrid vehicle control ECU
- Absorber control ECU*5
- Vehicle approaching speaker controller
- No. 4 CAN junction connector
- No. 7 CAN junction connector
Lexus NX: Check Bus 5 Line for Short to GND
Lexus NX Service Manual / Power Source & Network / Networking / Can Communication System / Check Bus 5 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 15 (CA5H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 16 (CA5L) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3.
| Symptom | Trouble Area |
|---|---|
|
*1: w/ Pre-collision System
*2: w/ Intuitive Parking Assist System *3: w/ Panoramic View Monitor System *4: w/ Blind Spot Monitor System *5: w/ Adaptive Variable Suspension System | |
| There is no resistance between terminal 15 (CA5H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 16 (CA5L) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3. | |
WIRING DIAGRAM
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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 SHORT TO GND 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.
| *a | Front view of wire harness connector (to No. 4 CAN Junction Connector) | *b | to Vehicle Approaching Speaker Controller |
| *c | to Central Gateway ECU (Network Gateway ECU) | *d | to Millimeter Wave Radar Sensor Assembly (w/ Pre-collision System) |
| *e | to Clearance Warning ECU Assembly (w/ Intuitive Parking Assist System) | *f | to Forward Recognition Camera (w/ Pre-collision System) |
| *g | to No. 7 CAN Junction Connector | *h | Front view of DLC3 |
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition | Connected to |
|---|---|---|---|
|
*1: w/ Pre-collision System
*2: w/ Intuitive Parking Assist System | |||
| I95-2 (CANH) - I182-4 (CG) | Cable disconnected from negative (-) auxiliary battery terminal | 200 Ω or higher | Vehicle approaching speaker controller |
| I95-12 (CANL) - I182-4 (CG) | |||
| I95-3 (CANH) - I182-4 (CG) | Cable disconnected from negative (-) auxiliary battery terminal | 200 Ω or higher | Central gateway ECU (network gateway ECU) |
| I95-13 (CANL) - I182-4 (CG) | |||
| I95-4 (CANH) - I182-4 (CG) | Cable disconnected from negative (-) auxiliary battery terminal | 200 Ω or higher | Millimeter wave radar sensor assembly*1 |
| I95-14 (CANL) - I182-4 (CG) | |||
| I95-6 (CANH) - I182-4 (CG) | Cable disconnected from negative (-) auxiliary battery terminal | 200 Ω or higher | Clearance warning ECU assembly*2 |
| I95-16 (CANL) - I182-4 (CG) | |||
| I95-8 (CANH) - I182-4 (CG) | Cable disconnected from negative (-) auxiliary battery terminal | 200 Ω or higher | Forward recognition camera*1 |
| I95-18 (CANL) - I182-4 (CG) | |||
| I95-9 (CANH) - I182-4 (CG) | Cable disconnected from negative (-) auxiliary battery terminal | 200 Ω or higher | No. 7 CAN junction connector |
| I95-19 (CANL) - I182-4 (CG) | |||
| Result | Proceed to |
|---|---|
| OK | A |
| NG (Central gateway ECU [network gateway ECU] main wire) | B |
| NG (No. 7 CAN junction connector CAN main wire) | C |
| NG (Wire to ECU or sensor) | D |
| A | .gif) | REPLACE NO. 4 CAN JUNCTION CONNECTOR |
| C | | GO TO STEP 4 |
| D | | GO TO STEP 6 |
|
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| 2. | CONNECT CONNECTOR |
(a) Reconnect the I95 No. 4 CAN junction connector.
|
| 3. | CHECK FOR SHORT TO GND 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.
| *a | Front view of wire harness connector (to Central Gateway ECU [Network Gateway ECU]) | *b | Front view of DLC3 |
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| I160-15 (CA5H) - I182-4 (CG) | Cable disconnected from negative (-) auxiliary battery terminal | 200 Ω or higher |
| I160-16 (CA5L) - I182-4 (CG) |
| OK | | REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) |
| NG | | REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU] - NO. 4 CAN JUNCTION CONNECTOR) |
| 4. | CONNECT CONNECTOR |
(a) Reconnect the I95 No. 4 CAN junction connector.
|
| 5. | CHECK FOR SHORT TO GND IN CAN BUS WIRE (NO. 7 CAN JUNCTION CONNECTOR) |
(a) Disconnect the No. 7 CAN junction connector.
| *a | Front view of wire harness connector (to No. 7 CAN Junction Connector) | *b | to Parking Assist ECU (w/ Panoramic View Monitor System) |
| *c | to Blind Spot Monitor Sensor LH (w/ Blind Spot Monitor System) | *d | to Hybrid Vehicle Control ECU |
| *e | to No. 4 CAN Junction Connector | *f | to Absorber Control ECU (w/ Adaptive Variable Suspension System) |
| *g | to Rear Television Camera Assembly | *h | Front view of DLC3 |
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition | Connected to |
|---|---|---|---|
|
*1: w/ Panoramic View Monitor System
*2: w/ Blind Spot Monitor System *3: w/ Adaptive Variable Suspension System | |||
| Q32-2 (CANH) - I182-4 (CG) | Cable disconnected from negative (-) auxiliary battery terminal | 200 Ω or higher | Parking assist ECU*1 |
| Q32-12 (CANL) - I182-4 (CG) | |||
| Q32-3 (CANH) - I182-4 (CG) | Cable disconnected from negative (-) auxiliary battery terminal | 200 Ω or higher | Blind spot monitor sensor LH*2 |
| Q32-13 (CANL) - I182-4 (CG) | |||
| Q32-4 (CANH) - I182-4 (CG) | Cable disconnected from negative (-) auxiliary battery terminal | 200 Ω or higher | Hybrid Vehicle Control ECU |
| Q32-14 (CANL) - I182-4 (CG) | |||
| Q32-5 (CANH) - I182-4 (CG) | Cable disconnected from negative (-) auxiliary battery terminal | 200 Ω or higher | No. 4 CAN junction connector |
| Q32-15 (CANL) - I182-4 (CG) | |||
| Q32-7 (CANH) - I182-4 (CG) | Cable disconnected from negative (-) auxiliary battery terminal | 200 Ω or higher | Absorber control ECU*3 |
| Q32-17 (CANL) - I182-4 (CG) | |||
| Q32-8 (CANH) - I182-4 (CG) | Cable disconnected from negative (-) auxiliary battery terminal | 200 Ω or higher | Rear television camera assembly |
| Q32-18 (CANL) - I182-4 (CG) | |||
| Result | Proceed to |
|---|---|
| OK | A |
| NG (No. 7 CAN junction connector CAN main wire) | B |
| NG (Wire to ECU or sensor) | C |
| A | | REPLACE NO. 7 CAN JUNCTION CONNECTOR |
| B | | REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (NO. 7 CAN JUNCTION CONNECTOR - NO. 4 CAN JUNCTION CONNECTOR) |
| C | | GO TO STEP 6 |
| 6. | CHECK FOR SHORT TO GND IN CAN BUS WIRE (ECU, SENSOR) |
(a) Reconnect all wire harness connectors.
(b) Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the bus line shorted to GND is connected.
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(c) Measure the resistance according to the value(s) in the table below.
| *a | Component with harness connected (Central Gateway ECU [Network Gateway ECU]) | *b | Front view of DLC3 |
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| I160-15 (CA5H) - I182-4 (CG) | Cable disconnected from negative (-) auxiliary battery terminal | 200 Ω or higher |
| I160-16 (CA5L) - I182-4 (CG) |
HINT:
If the resistance changes to 200 Ω or higher when the connector is disconnected from the ECU or sensor, there may be a short in the ECU or sensor.
| OK | | REPLACE ECU OR SENSOR |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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