Toyota Tacoma 2015-2018 Service Manual: Main Body ECU Communication Stop Mode

Toyota Tacoma 2015-2018 Service Manual / Can Communication / Can Communication System / Main Body ECU Communication Stop Mode

DESCRIPTION

Detection Item	Symptom	Trouble Area
Main Body ECU Communication Stop Mode	Either condition is met: Communication stop for "Main Body" is indicated on the "Communication Bus Check" screen of the Techstream. Click here Communication system DTCs (DTCs that start with U) that correspond to "Main Body ECU Communication Stop Mode" in "DTC Combination Table" are output. Click here	Main body ECU (multiplex network body ECU) branch line or connector Power source circuit of main body ECU (multiplex network Body ECU) or driver side junction block Main body ECU (multiplex network body ECU) ground circuit or driver side junction block Main body ECU (multiplex network body ECU) or driver side junction block

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 (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
After turning the ignition 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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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.
If the main body ECU (multiplex network body ECU) is replaced, 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) BRANCH LINE)

(a) Disconnect the cable from the negative (-) battery terminal.

(b) Disconnect the main body ECU (multiplex network body ECU) connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
M6-14 (CANH) - M6-13 (CANL)	Cable disconnected from negative (-) battery terminal	54 to 69 Ω

Text in Illustration

*a	Front view of wire harness connector (to Main Body ECU (Multiplex Network Body ECU))

REPAIR OR REPLACE CAN BRANCH LINE 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:

Tester Connection	Condition	Specified Condition
MB-11 (GND1) - Body ground	Cable disconnected from negative (-) battery terminal	Below 1 Ω

(d) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
MB-30 (ACC) - Body ground	Ignition switch ACC	11 to 14 V
MB-31 (BECU) - Body ground	Always	11 to 14 V
MB-32 (IG) - Body ground	Ignition switch ON	11 to 14 V

Text in Illustration

*1	Driver Side Junction Block

Result

Result	Proceed to
OK	A
NG (for BECU circuit)	B
NG (for ACC circuit)	C
NG (for IG circuit)	D
NG (for GND1 circuit)	E

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

GO TO LIGHTING SYSTEM (ACC SIGNAL CIRCUIT)

GO TO LIGHTING SYSTEM (IG SIGNAL CIRCUIT)

GO TO STEP 4

3.	CHECK HARNESS AND CONNECTOR (BECU CIRCUIT)

(a) Disconnect the driver side junction block connector.

(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection	Condition	Specified Condition
1F-15 - Body ground	Always	11 to 14 V

Text in Illustration

*a	Front view of wire harness connector (to Driver Side Junction Block)

REPLACE DRIVER SIDE JUNCTION BLOCK

REPAIR OR REPLACE HARNESS OR CONNECTOR (BECU CIRCUIT)

4.	CHECK HARNESS AND CONNECTOR (GND1 CIRCUIT)

(a) Disconnect the driver side junction block connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
1D-5 - Body ground	Always	Below 1 Ω

Text in Illustration

*a	Front view of wire harness connector (to Driver Side Junction Block)

REPLACE DRIVER SIDE JUNCTION BLOCK

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

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