DTC U1002: Lost Communication with Gateway Module (Main Body ECU) [09/2017 - 05/2019]: Description

The main body ECU (multiplex network body ECU) will store this DTC when no signals can be received from the ECUs that have been memorized as those that are connected to sub bus 1.
When the main body ECU (multiplex network body ECU) receives a response signal from the ECUs connected to sub bus 1, the main body ECU (multiplex network body ECU) recognizes and memorizes that the ECU is connected to sub bus 1. Based on this memorized data, the main body ECU (multiplex network body ECU) monitors for malfunctions in the ECUs connected to sub bus 1 when communicating with those ECUs. If the main body ECU (multiplex network body ECU) cannot receive response signals from the ECUs that have been memorized as those connected to sub bus 1, the main body ECU (multiplex network body ECU) determines that a malfunction exists.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	DTC Output from
U1002	Lost Communication with Gateway Module (Main Body ECU)	The main body ECU (multiplex network body ECU) cannot receive signals from all ECUs that have been memorized as those connected to sub bus 1.	Open or short in sub bus 1 main lines or connector Short in sub bus 1 branch lines or connector Main body ECU (multiplex network body ECU) Front power seat switch (for Driver Side) (w/ Memory) Multiplex tilt and telescopic ECU (for Power Tilt and Power Telescopic Steering Column) Multiplex network door ECU (w/ Power Back Door System) Outer mirror control ECU assembly LH (w/ Memory) Outer mirror control ECU assembly RH (w/ Memory) Open or short in No. 4 CAN junction connector Open or short in No. 5 CAN junction connector Open or short in No. 7 CAN junction terminal Open or short in No. 2 CAN junction terminal	Main body ECU (multiplex network body ECU)

HINT:

This diagnostic procedure is for when DTC U1002 is output by the main body ECU (multiplex network body ECU) (Techstream display: Main Body).