Toyota Yaris: Can Communication System / Main Body ECU Communication Stop Mode
DESCRIPTION
| Detection Item | Symptom | Trouble Area |
|---|---|---|
| Main Body ECU Communication Stop Mode | Communication stop for "Main Body" is indicated on the "Communication Bus Check" screen of the GTS. Click here
|
|
WIRING DIAGRAM
CAUTION / NOTICE / HINT
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
NOTICE:
-
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 ignition 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.
-
After the ignition switch is turned off, there may be a waiting time before disconnecting the negative (-) auxiliary battery terminal.
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-
When disconnecting and reconnecting the auxiliary battery, there is an automatic learning function that completes learning when the respective system is used.
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-
Some parts must be initialized and set when replacing or removing and installing parts.
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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 ignition switch to ON 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.
-
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.
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Before replacing the main body ECU (multiplex network body ECU), 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 OPEN IN CAN BUS LINES (MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) MAIN LINE) |
(a) Disconnect the cable from the negative (-) auxiliary battery terminal.
(b) Disconnect the main body ECU (multiplex network body ECU) connector.
| (c) Measure the resistance according to the value(s) in the table below. Standard Resistance:
|
|
| NG |
 | REPAIR OR REPLACE CAN MAIN BUS 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 power distribution box assembly. |
|
(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-26 (BECU) - Body ground | Ignition switch off | 11 to 14 V |
| MB-27 (IGR) - Body ground | Ignition switch ON | 11 to 14 V |
| MB-27 (IGR) - Body ground | Ignition switch off | Below 1 V |
NOTICE:
Perform this inspection with the wire harness connected to the power distribution box assembly.
| Result | Proceed to |
|---|---|
| OK | A |
| NG (BECU) | B |
| NG (IGR) | C |
| NG (GND1) | D |
| NG (GND2) | E |
| A |
 | REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) |
| C |
 | GO TO LIGHTING (INT) SYSTEM (IG SIGNAL CIRCUIT) |
| D |
 | GO TO STEP 4 |
| E |
 | GO TO STEP 5 |
|
| 3. | CHECK HARNESS AND CONNECTOR (BECU SIGNAL CIRCUIT) |
(a) Disconnect the cable from the negative (-) auxiliary battery terminal.
(b) Disconnect the power distribution box assembly connector.
(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:
|
|
| OK |
 | REPLACE POWER DISTRIBUTION BOX 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 power distribution box assembly connector.
| (c) Measure the resistance according to the value(s) in the table below. Standard Resistance:
|
|
| OK |
 | REPLACE POWER DISTRIBUTION BOX ASSEMBLY |
| NG |
 | REPAIR OR REPLACE HARNESS OR CONNECTOR (GROUND CIRCUIT) |
| 5. | CHECK HARNESS AND CONNECTOR (GROUND CIRCUIT) |
(a) Disconnect the cable from the negative (-) auxiliary battery terminal.
(b) Disconnect the power distribution box assembly connector.
| (c) Measure the resistance according to the value(s) in the table below. Standard Resistance:
|
|
| OK |
 | REPLACE POWER DISTRIBUTION BOX ASSEMBLY |
| NG |
 | REPAIR OR REPLACE HARNESS OR CONNECTOR (GROUND CIRCUIT) |
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