Lexus ES: Check Bus 2 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 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway ECU) is below 54 Ω.
| Symptom | Trouble Area |
|---|---|
| Resistance between terminals 18 (CA4H) and 17 (CA4L) 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. 2 JUNCTION CONNECTOR) |
(a) Disconnect the cable from the negative (-) battery terminal.
(b) Disconnect the A71 No. 2 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 Junction Connector) | *b | to No. 4 CAN Junction Connector |
| *c | to ECM | - | - |
Standard Resistance:
| Tester Connection | Condition | Specified Condition | Connected to |
|---|---|---|---|
| A71-8 (CANH) - A71-19 (CANL) | Cable disconnected from negative (-) battery terminal | 108 to 132 Ω | No. 4 CAN junction connector |
| A71-11 (CANH) - A71-22 (CANL) | Cable disconnected from negative (-) battery terminal | 108 to 132 Ω | ECM |
| Result | Proceed to |
|---|---|
| OK | A |
| NG (Line to ECM) | B |
| NG (Line to No. 4 CAN junction connector) | C |
| A | .gif) | REPLACE NO. 2 JUNCTION CONNECTOR |
| C | | GO TO STEP 3 |
|
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| 2. | CHECK FOR SHORT IN CAN BUS LINES (NO. 2 JUNCTION CONNECTOR - ECM) |
(a) Disconnect the A25 ECM 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 Junction Connector) | *b | to ECM |
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| A71-11 (CANH) - A71-22 (CANL) | Cable disconnected from negative (-) battery terminal | 1 MΩ or higher |
| OK | | REPLACE ECM |
| NG | | REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 2 JUNCTION CONNECTOR - ECM) |
| 3. | CHECK FOR SHORT IN CAN BUS LINES (NO. 4 CAN JUNCTION CONNECTOR - NO. 2 JUNCTION CONNECTOR) |
(a) Disconnect the G99 No. 4 CAN junction connector.
(b) Measure the resistance according to the value(s) in the table below.
| *a | Front view of wire harness connector (to No. 4 CAN Junction Connector) | *b | to No. 2 Junction Connector |
Standard Resistance:
| Tester Connection | Condition | Specified Condition | Connected to |
|---|---|---|---|
| G99-11 (CANH) - G99-22 (CANL) | Cable disconnected from negative (-) battery terminal | 1 MΩ or higher | No. 2 junction connector |
| NG | | REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 4 CAN JUNCTION CONNECTOR - NO. 2 JUNCTION CONNECTOR) |
|
| 4. | CHECK FOR SHORT IN CAN BUS LINES (NO. 4 CAN JUNCTION CONNECTOR) |
(a) Disconnect the G98 No. 4 CAN junction connector.
(b) Measure the resistance according to the value(s) in the table below.
| *a | Front view of wire harness connector (to No. 4 CAN Junction Connector) | *b | to Central Gateway ECU (Network Gateway ECU) |
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| G98-1 (CANH) - G98-12 (CANL) | Cable disconnected from negative (-) battery terminal | 108 to 132 Ω |
| OK | | REPLACE NO. 4 CAN JUNCTION CONNECTOR |
|
| 5. | CHECK FOR SHORT IN CAN BUS LINES (NO. 4 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. 4 CAN Junction Connector) | *b | to Central Gateway ECU (Network Gateway ECU) |
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| G98-1 (CANH) - G98-12 (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. 4 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)) |
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