DTC U0104: Lost Communication with Driving Support ECU [10/2014 - 10/2015]: Procedure

1. Reconfirm DTCs.

   HINT: 

   If DTC U1002 is output from PM1 Gateway of the power management control ECU, this indicates a sub bus 11 malfunction. Troubleshoot for DTC U1002 and check for malfunctions in sub bus 11.

   Result

   Result	Proceed to
   U1002 is not output from power management control ECU (Techstream display: PM1 Gateway)	A
   U1002 is output from power management control ECU (Techstream display: PM1 Gateway)	B

Result: 

B 

GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC 

(Refer to DTC U1002: Lost Communication with Gateway Module [10/2014 - 10/2015] )

Result: 

A 

See step  2

1. Disconnect the cable from the negative (-) auxiliary battery terminal.
2. Disconnect the D38 driving support ECU assembly connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   D38-39 (CA2H) - D38-17 (CA2L)	Cable disconnected from negative (-) auxiliary battery terminal	54 to 69 Ω

   TEXT IN ILLUSTRATION
   
   

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

Result: 

NG 

REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (DRIVING SUPPORT ECU ASSEMBLY) 

Result: 

OK 

See step  3

1. 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
   D38-25 (GND) - Body ground	Cable disconnected from negative (-) auxiliary battery terminal	Below 1 Ω

   TEXT IN ILLUSTRATION
   
   

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

2. Connect the cable to the negative (-) auxiliary battery terminal.
3. Measure the voltage according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   D38-30 (B) - Body ground	Power switch on (IG)	11 to 14 V

   TEXT IN ILLUSTRATION
   
   

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

Result: 

OK 

REPLACE DRIVING SUPPORT ECU ASSEMBLY 

(Refer to REMOVAL [10/2014 - 10/2015] )

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)