Lexus ES: Check Bus 3 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 6 (CA3H) and 21 (CA3L) of the central gateway ECU (network gateway ECU) is below 54 Ω.
| Symptom | Trouble Area |
|---|---|
| Resistance between terminals 6 (CA3H) and 21 (CA3L) 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.
Click here
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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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Before replacing the DCM (telematics transceiver), refer to Registration.
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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. 4 CAN JUNCTION CONNECTOR) |
(a) Disconnect the cable from the negative (-) battery terminal.
(b) Disconnect the G98 No. 4 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. 4 CAN Junction Connector) | *b | to DCM (Telematics Transceiver) (w/ Telematics Transceiver) |
| *c | to Central Gateway ECU (Network Gateway ECU) | *d | to Option Connector (Bus Buffer ECU) (w/ CAN Compatible Optional Devices) |
Standard Resistance:
| Tester Connection | Condition | Specified Condition | Connected to |
|---|---|---|---|
| G98-8 (CANH) - G98-19 (CANL) | Cable disconnected from negative (-) battery terminal | 200 Ω or higher | DCM (telematics transceiver)*1 |
| G98-9 (CANH) - G98-20 (CANL) | Cable disconnected from negative (-) battery terminal | 108 to 132 Ω | Central gateway ECU (network gateway ECU) |
| G98-10 (CANH) - G98-21 (CANL) | Cable disconnected from negative (-) battery terminal | 200 Ω or higher*2 1 MΩ or higher*3 | Option connector (bus buffer ECU)*2 |
| G98-11 (CANH) - G98-22 (CANL) | Cable disconnected from negative (-) battery terminal | 108 to 132 Ω | Central gateway ECU (network gateway ECU) |
- *1: w/ Telematics Transceiver
- *2: w/ CAN Compatible Optional Devices
- *3: w/o CAN Compatible Optional Devices
HINT:
If there is a short in a CAN bus line without any CAN compatible optional devices connected to the option connector, repair or replace the CAN bus branch line or the option connector.
| Result | Proceed to |
|---|---|
| OK | A |
| NG (Line to central gateway ECU (network gateway ECU)) | B |
| NG (Line to ECU or sensor) | C |
| B | .gif) | GO TO STEP 3 |
| C | | GO TO STEP 4 |
|
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| 2. | CHECK FOR SHORT IN CAN BUS LINES (NO. 4 CAN JUNCTION CONNECTOR) |
(a) Disconnect the G99 No. 4 CAN junction 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 Radio Receiver Assembly |
| *c | to Stereo Component Equalizer Assembly (w/ Active Noise Control System) | - | - |
Standard Resistance:
| Tester Connection | Condition | Specified Condition | Connected to |
|---|---|---|---|
| G99-1 (CANH) - G99-12 (CANL) | Cable disconnected from negative (-) battery terminal | 200 Ω or higher | Radio receiver assembly |
| G99-2 (CANH) - G99-13 (CANL) | Cable disconnected from negative (-) battery terminal | 200 Ω or higher | Stereo component equalizer assembly* |
- *: w/ Active Noise Control System
| OK | | REPLACE NO. 4 CAN JUNCTION CONNECTOR |
| NG | | GO TO STEP 4 |
| 3. | 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 |
|---|---|---|
| G98-9 (CANH) - G98-20 (CANL) | Cable disconnected from negative (-) battery terminal | 1 MΩ or higher |
| G98-11 (CANH) - G98-22 (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)) |
| 4. | 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 6 (CA3H) and 21 (CA3L) of the central gateway ECU (network gateway ECU) is 70 Ω or high
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