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Communication stop for "Main Body" is indicated on the "Communication Bus Check" screen of the Techstream.
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![2020 MY Corolla Corolla HV [01/2019 - 04/2020]; NETWORKING: CAN COMMUNICATION SYSTEM (for HV Model): PROBLEM SYMPTOMS TABLE](/t3Portal/stylegraphics/info.gif)
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Communication stop history for "Main Body" is indicated on the "Communication Bus Check (Detail)" screen of the Techstream. (The Lost Communication Time value for "Main Body" is 6 or more.)
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Communication system DTCs (DTCs that start with U) that correspond to "Main Body ECU Communication Stop Mode" in "DTC Combination Table" are output.
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| Last Modified: 05-13-2024 | 6.11:8.1.0 | Doc ID: RM100000001GVYQ |
| Model Year Start: 2020 | Model: Corolla | Prod Date Range: [01/2019 - 09/2022] |
| Title: NETWORKING: CAN COMMUNICATION SYSTEM (for HV Model): Main Body ECU Communication Stop Mode; 2020 - 2022 MY Corolla Corolla HV [01/2019 - 09/2022] | ||
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Main Body ECU Communication Stop Mode |
DESCRIPTION
|
Detection Item |
Symptom |
Trouble Area |
|---|---|---|
|
Main Body ECU 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 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. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary 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 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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- Inspect the fuses for circuits related to this system before performing the following procedure.
- Before replacing the main body ECU (multiplex network body ECU), refer to Service Bulletin.
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 (MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) BRANCH LINE) |
(a) Disconnect the cable from the negative (-) auxiliary battery terminal.
(b) Disconnect the I85 main body ECU (multiplex network body ECU) connector.
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(c) Measure the resistance according to the value(s) in the table below. Standard Resistance:
|
|
| NG |
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REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)) |
|
|
2. |
CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT) |
(a) Remove the main body ECU (multiplex network body ECU).
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(b) Measure the resistance according to the value(s) in the table below. Standard Resistance:
NOTICE: Perform this inspection with the wire harness connected to the instrument panel junction block assembly. |
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(c) Reconnect the cable to the negative (-) auxiliary battery terminal.
(d) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
MB-30 (ACC) - Body ground |
Power switch on (ACC) |
11 to 14 V |
|
MB-31 (BECU) - Body ground |
Power switch off |
11 to 14 V |
|
MB-32 (IG) - Body ground |
Power switch on (IG) |
11 to 14 V |
NOTICE:
Perform this inspection with the wire harness connected to the instrument panel junction block assembly.
|
Result |
Proceed to |
|---|---|
|
OK |
A |
|
NG (BECU) |
B |
|
NG (ACC) |
C |
|
NG (IG) |
D |
|
NG (GND1) |
E |
| A |
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REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)
|
| C |
|
| D |
|
| E |
|
|
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3. |
CHECK HARNESS AND CONNECTOR (BECU SIGNAL CIRCUIT) |
(a) Disconnect the cable from the negative (-) auxiliary battery terminal.
(b) Disconnect the 4B instrument panel junction block assembly connector.
(c) Reconnect the cable to the negative (-) auxiliary battery terminal.
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(d) Measure the voltage according to the value(s) in the table below. Standard Voltage:
|
|
| OK |
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REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY
|
| NG |
|
REPAIR OR REPLACE HARNESS OR CONNECTOR (BECU SIGNAL CIRCUIT) |
|
4. |
CHECK HARNESS AND CONNECTOR (GROUND CIRCUIT) |
(a) Disconnect the cable from the negative (-) auxiliary battery terminal.
(b) Disconnect the 4F instrument panel junction block assembly connector.
|
(c) Measure the resistance according to the value(s) in the table below. Standard Resistance:
|
|
| OK |
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REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY
|
| NG |
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REPAIR OR REPLACE HARNESS OR CONNECTOR (GROUND CIRCUIT) |
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