Lexus ES: Headlight ECU LH Communication Stop Mode
DESCRIPTION
| Detection Item | Symptom | Trouble Area |
|---|---|---|
| Headlight ECU LH Communication Stop Mode | Any of the following conditions are met:
|
|
WIRING DIAGRAM
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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- Inspect the fuses for circuits related to this system before performing the following procedure.
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 OPEN IN CAN BUS LINES (HEADLIGHT ECU SUB-ASSEMBLY LH BRANCH LINE) |
(a) Disconnect the cable from the negative (-) battery terminal.
(b) Disconnect the A78 headlight ECU sub-assembly LH connector.
| (c) Measure the resistance according to the value(s) in the table below. Standard Resistance:
|
|
| NG | .gif) | REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (HEADLIGHT ECU SUB-ASSEMBLY LH) |
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| 2. | CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT) |
| (a) Measure the resistance according to the value(s) in the table below. Standard Resistance:
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(b) Reconnect the cable to the negative (-) battery terminal.
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| A78-4 (IG) - Body ground | Engine switch on (IG) | 11 to 14 V |
| OK | | REPLACE HEADLIGHT ECU SUB-ASSEMBLY LH |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT) |
