Toyota 4Runner: Main Body ECU Communication Stop Mode

Toyota 4Runner Service Manual / Power Source / Network / Networking / 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: "Main Body" is not displayed on the "CAN Bus Check" screen. "Main Body ECU Communication Stop Mode" in "DTC Combination Table" applies.	Power source or inside main body ECU (multiplex network body ECU) Main body ECU (multiplex network body ECU) branch wire or connector Main body ECU (multiplex network body ECU)

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

HINT:

Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

PROCEDURE

1.	DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL

(a) Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the main wire and branch wire.

CAUTION:

Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

NOTICE:

When disconnecting the cable, some systems need to be initialized after the cable is reconnected (See page ).

2.	CHECK FOR OPEN IN CAN BUS WIRE (MAIN BODY ECU BRANCH WIRE)

(a) Disconnect the F9 main body ECU (multiplex network body ECU) connector.

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

Standard Resistance:

Tester Connection	Switch Condition	Specified Condition
F9-14 (CANH) - F9-13 (CANL)	Ignition switch off	54 to 69 Ω

Text in Illustration

*a	Rear view of wire harness connector (to Main Body ECU [Multiplex Network Body ECU])

REPAIR OR REPLACE MAIN BODY ECU BRANCH WIRE OR CONNECTOR (CANH, CANL)

3.	CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - BATTERY AND BODY GROUND)

(a) Connect the cable to the negative (-) battery terminal.

NOTICE:

When disconnecting the cable, some systems need to be initialized after the cable is reconnected (See page ).

Text in Illustration

Rear view of wire harness connector

(to Main Body ECU [Multiplex Network Body ECU])

Front view of wire harness connector

(to Main Body ECU [Multiplex Network Body ECU])

(b) Remove the main body ECU (multiplex network body ECU) (See page ).

Standard Resistance:

Tester Connection	Condition	Specified Condition
F10-3 (GND2) - Body ground	Always	Below 1 Ω
A-11 (GND1) - Body ground	Always	Below 1 Ω

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

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
A-32 (IG) - Body ground	Ignition switch ON	11 to 14 V
A-31 (ALTB) - Body ground	Always	11 to 14 V
A-30 (BECU) - Body ground	Always	11 to 14 V
A-29 (ACC) - Body ground	Ignition switch ACC	11 to 14 V

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

REPAIR OR REPLACE HARNESS OR CONNECTOR

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