DTC U0104: Lost Communication with Driving Support ECU [08/2015 - ]: Procedure

RECONFIRM DTC OUTPUT

Reconfirm DTCs.

HINT:

If DTC U1002 is output from Gateway of the network gateway ECU, this indicates a sub bus 2 malfunction. Troubleshoot for DTC U1002 and check for malfunctions in sub bus 2.

Result

Result	Proceed to
DTC U1002 is not output from the network gateway ECU (Techstream display: Gateway)	A
DTC U1002 is output from the network gateway ECU (Techstream display: Gateway)	B

B → See step 5

A: Go to next step

CHECK FOR OPEN IN SUB BUS 2 LINES (DRIVING SUPPORT ECU ASSEMBLY BRANCH LINE)

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

Disconnect the I187 driving support ECU assembly connector.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

Standard Resistance

Tester Connection	Condition	Specified Condition
I187-39 (CA2H) - I187-17 (CA2L)	Cable disconnected from negative (-) battery terminal	54 to 69 Ω

TEXT IN ILLUSTRATION

*a	Front view of wire harness connector (to Driving Support ECU Assembly)

NG → REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (DRIVING SUPPORT ECU ASSEMBLY)

OK: Go to next step

CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Standard Resistance

Tester Connection	Condition	Specified Condition
I187-25 (GND) - Body ground	Cable disconnected from negative (-) battery terminal	Below 1 Ω

TEXT IN ILLUSTRATION

*a	Front view of wire harness connector (to Driving Support ECU Assembly)

Reconnect the cable to the negative (-) battery terminal.

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

Standard Voltage

Tester Connection	Condition	Specified Condition
I187-30 (B) - Body ground	Ignition switch ON	11 to 14 V

TEXT IN ILLUSTRATION

*a	Front view of wire harness connector (to Driving Support ECU Assembly)

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

OK → See step 4

REPLACE DRIVING SUPPORT ECU ASSEMBLY. Refer to REMOVAL [08/2015 - ]
GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC. Refer to DTC U1002: Lost Communication with Gateway Module (Network Gateway ECU); DTC U0265: Lost Communication with Parking Assist Monitor Module [08/2015 - ]