DTC U1002: Lost Communication with Gateway Module (Main Body) [09/2016 - 09/2017]: Description

The main body ECU (multiplex network body ECU) stores this DTC when no signals can be received from the ECUs that have been memorized as those connected to the sub bus 1.
When the main body ECU (multiplex network body ECU) receives a response signal from the ECUs connected to the sub bus 1, the main body ECU (multiplex network body ECU) recognizes and memorizes that the ECU is connected to the sub bus 1. Based on this memorized data, the main body ECU (multiplex network body ECU) monitors for malfunctions in the ECUs connected to the 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 the sub bus 1, the main body ECU (multiplex network body ECU) determines that a malfunction exists.
If 2 or more DTCs are output during the DTC check, one side of the CAN branch wire may be open (one side of the CANH [CAN branch wire]/CANL [CAN branch wire] of the ECU and/or sensor is open).

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	DTC Output from
U1002	Lost Communication with Gateway Module (Main Body)	Lost communication with the gateway module.	Open or short in sub bus 1 main wire or connector Open or short in sub bus 1 branch wire or connector Main body ECU (multiplex network body ECU) Multiplex tilt and telescopic ECU1 Outer mirror control ECU assembly RH2 Outer mirror control ECU assembly LH2 Front power seat switch LH2 Headlight light control ECU sub-assembly LH3 Multiplex network door ECU4 Rear television camera assembly No. 4 CAN junction connector No. 5 CAN junction connector No. 7 CAN junction connector No. 2 CAN junction terminal	Main body ECU (multiplex network body ECU)