Lexus ES: Check Bus 4 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 22 (CA2H) and 7 (CA2L) of the central gateway ECU (network gateway ECU) is below 54 Ω.
| Symptom | Trouble Area |
|---|---|
| Resistance between terminals 22 (CA2H) and 7 (CA2L) of the central gateway ECU (network gateway ECU) is below 54 Ω. |
|
WIRING DIAGRAM
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CAUTION / NOTICE / HINT
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
NOTICE:
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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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- Before measuring the resistance of the CAN bus, turn the engine 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 (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
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After turning the engine switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work.
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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 engine 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:
- Before disconnecting related connectors for inspection, push in on each connector body to check that the connector is not loose or disconnected.
- When a connector is disconnected, check that the terminals and connector body are not cracked, deformed or corroded.
PROCEDURE
| 1. | CHECK FOR SHORT IN CAN BUS LINES (NO. 7 CAN JUNCTION CONNECTOR) |
(a) Disconnect the cable from the negative (-) battery terminal.
(b) Disconnect the N99 No. 7 CAN junction connector.
(c) Measure the resistance according to the value(s) in the table below.
| *a | Front view of wire harness connector (to No. 7 CAN Junction Connector) | *b | to Tire Pressure Warning ECU and Receiver |
| *c | to Occupant Detection ECU | *d | to Central Gateway ECU (Network Gateway ECU) |
| *e | to No. 4 CAN Junction Connector | *f | to Absorber Control ECU (w/ AVS System) |
Standard Resistance:
| Tester Connection | Condition | Specified Condition | Connected to |
|---|---|---|---|
| N99-1 (CANH) - N99-7 (CANL) | Cable disconnected from negative (-) battery terminal | 200 Ω or higher | Tire pressure warning ECU and receiver |
| N99-2 (CANH) - N99-8 (CANL) | Cable disconnected from negative (-) battery terminal | 200 Ω or higher | Occupant detection ECU |
| N99-3 (CANH) - N99-9 (CANL) | Cable disconnected from negative (-) battery terminal | 108 to 132 Ω | Central gateway ECU (network gateway ECU) |
| N99-4 (CANH) - N99-10 (CANL) | Cable disconnected from negative (-) battery terminal | 108 to 132 Ω | No. 4 CAN junction connector |
| N99-5 (CANH) - N99-11 (CANL) | Cable disconnected from negative (-) battery terminal | 200 Ω or higher | Absorber control ECU* |
- *: w/ AVS System
| Result | Proceed to |
|---|---|
| OK | A |
| NG (Line to central gateway ECU (network gateway ECU)) | B |
| NG (Line to No. 4 CAN junction connector) | C |
| NG (Line to ECU or sensor) | D |
| A | .gif) | REPLACE NO. 7 CAN JUNCTION CONNECTOR |
| C | | GO TO STEP 3 |
| D | | GO TO STEP 7 |
|
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| 2. | CHECK FOR SHORT IN CAN BUS LINES (NO. 7 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)) |
(a) Disconnect the G66 central gateway ECU (network gateway ECU) connector.
(b) Measure the resistance according to the value(s) in the table below.
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| *a | Front view of wire harness connector (to No. 7 CAN Junction Connector) | *b | to Central Gateway ECU (Network Gateway ECU) |
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| N99-3 (CANH) - N99-9 (CANL) | Cable disconnected from negative (-) battery terminal | 1 MΩ or higher |
| OK | | REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) |
| NG | | REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 7 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)) |
| 3. | CHECK FOR SHORT IN CAN BUS LINES (NO. 4 CAN JUNCTION CONNECTOR - NO. 7 CAN JUNCTION CONNECTOR) |
(a) Reconnect the N99 No. 7 CAN junction connector.
(b) Disconnect the G99 No. 4 CAN junction connector.
(c) Measure the resistance according to the value(s) in the table below.
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| *a | Front view of wire harness connector (to No. 4 CAN Junction Connector) | *b | to No. 7 CAN Junction Connector |
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| G99-6 (CANH) - G99-17 (CANL) | Cable disconnected from negative (-) battery terminal | 108 to 132 Ω |
| NG | | REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 4 CAN JUNCTION CONNECTOR - NO. 7 CAN JUNCTION CONNECTOR) |
|
| 4. | CHECK FOR SHORT IN CAN BUS LINES (NO. 4 CAN JUNCTION CONNECTOR) |
(a) Reconnect the G99 No. 4 CAN junction connector.
(b) Disconnect the G98 No. 4 CAN junction connector.
(c) Measure the resistance according to the value(s) in the table below.
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| *a | Front view of wire harness connector (to No. 4 CAN Junction Connector) | *b | to No. 2 CAN Junction Connector |
| *c | to Steering Sensor | - | - |
Standard Resistance:
| Tester Connection | Condition | Specified Condition | Connected to |
|---|---|---|---|
| G98-6 (CANH) - G98-17 (CANL) | Cable disconnected from negative (-) battery terminal | 108 to 132 Ω | No. 2 CAN junction connector |
| G98-7 (CANH) - G98-18 (CANL) | Cable disconnected from negative (-) battery terminal | 200 Ω or higher | Steering sensor |
| Result | Proceed to |
|---|---|
| OK | A |
| NG (Line to No. 2 CAN junction connector) | B |
| NG (Line to ECU or sensor) | C |
| A | | REPLACE NO. 4 CAN JUNCTION CONNECTOR |
| C | | GO TO STEP 7 |
|
| 5. | CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR) |
(a) Reconnect the G98 No. 4 CAN junction connector.
(b) Disconnect the A69 No. 2 CAN junction connector.
(c) Measure the resistance according to the value(s) in the table below.
| *a | Front view of wire harness connector (to No. 2 CAN Junction Connector) | *b | to Brake Actuator Assembly |
| *c | to Airbag ECU Assembly | *d | to Rack and Pinion Power Steering Gear Assembly |
| *e | to No. 4 CAN Junction Connector | - | - |
Standard Resistance:
| Tester Connection | Condition | Specified Condition | Connected to |
|---|---|---|---|
| A69-1 (CANH) - A69-11 (CANL) | Cable disconnected from negative (-) battery terminal | 200 Ω or higher | Brake actuator assembly |
| A69-2 (CANH) - A69-12 (CANL) | Cable disconnected from negative (-) battery terminal | 108 to 132 Ω | Airbag ECU assembly |
| A69-4 (CANH) - A69-14 (CANL) | Cable disconnected from negative (-) battery terminal | 200 Ω or higher | Rack and pinion power steering gear assembly |
| A69-5 (CANH) - A69-15 (CANL) | Cable disconnected from negative (-) battery terminal | 108 to 132 Ω | No. 4 CAN junction connector |
| Result | Proceed to |
|---|---|
| OK | A |
| NG (Line to airbag ECU assembly) | B |
| NG (Line to No. 4 CAN junction connector) | C |
| NG (Line to ECU or sensor) | D |
| A | | REPLACE NO. 2 CAN JUNCTION CONNECTOR |
| C | | REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 2 CAN JUNCTION CONNECTOR - NO. 4 CAN JUNCTION CONNECTOR) |
| D | | GO TO STEP 7 |
|
| 6. | CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR - AIRBAG ECU ASSEMBLY) |
(a) Disconnect the G64 airbag ECU assembly connector.
(b) Measure the resistance according to the value(s) in the table below.
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| *a | Front view of wire harness connector (to No. 2 CAN Junction Connector) | *b | to Airbag ECU Assembly |
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| A69-2 (CANH) - A69-12 (CANL) | Cable disconnected from negative (-) battery terminal | 1 MΩ or higher |
| OK | | REPLACE AIRBAG ECU ASSEMBLY |
| NG | | REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 2 CAN JUNCTION CONNECTOR - AIRBAG ECU ASSEMBLY) |
| 7. | CHECK FOR SHORT IN CAN BUS LINES (ECU OR 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 short circuited branch line is connected.
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| (c) Measure the resistance according to the value(s) in the table below. Standard Resistance:
HINT:
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| OK | | REPLACE ECU OR SENSOR |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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DESCRIPTION There may be an open circuit in one of the CAN main bus lines when the resistance between terminals 22 (CA2H) and 7 (CA2L) of the central gateway ECU (network gateway ECU) is 70 Ω or high
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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
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