CAN COMMUNICATION SYSTEM, Diagnostic DTC:U1002

DTC Code	DTC Name
U1002	Lost Communication with Gateway Module (MS Bus)

DESCRIPTION

The main body ECU stores this DTC when no signals can be received from the ECUs that have been memorized as those connected to the CAN MS bus.
When the main body ECU receives a response signal from an ECU connected to the CAN MS bus, the main body ECU recognizes and memorizes that the ECU is connected to the CAN MS bus. Based on this memorized data, the main body ECU monitors for malfunctions in the ECUs connected to the CAN MS bus when communicating with those ECUs. If the main body ECU cannot receive response signals from the ECUs that have been memorized as those connected to the CAN MS bus, the main 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 Code	DTC Detection Condition	Trouble Area
U1002	Lost communication with the gateway module (MS bus).	MS bus circuit Main body ECU (instrument panel junction block assembly) CAN main wire or connector Position control ECU assembly CAN branch wire or connector Main body ECU (instrument panel junction block assembly) Position control ECU assembly

For vehicles with a seat position memory system.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

Note

Inspect the fuses for circuits related to this system before performing the following inspection procedure.
As the door control battery is installed between the vehicle battery and main body ECU (instrument panel junction block assembly), first perform the inspections in On-Vehicle Inspection to confirm that there are no malfunctions in the power source circuit for the main body ECU (instrument panel junction block assembly) before performing this troubleshooting procedure Click here.

Tech Tips

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

PROCEDURE

PRECAUTION

Note

After turning the ignition switch off, waiting time may be required before disconnecting the cable from the battery terminal. Therefore, make sure to read the disconnecting the cable from the battery terminal notice before proceeding with work Click here.

NEXT
DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL
1. Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the CAN main wire and the CAN branch wire.
  
  CAUTION:
  
  Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.
  
  Note
  
  When disconnecting the cable, some systems need to be initialized after the cable is reconnected Click here.
NEXT

CHECK CAN BUS WIRE (CAN MAIN WIRE FOR DISCONNECTION, CHECK BUS LINE FOR SHORT CIRCUIT)

Text in Illustration
*a	Component with harness connected (Main Body ECU [Instrument Panel Junction Block Assembly])

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

Standard Resistance

Tester Connection	Switch Condition	Specified Condition	Resistance: Malfunction
D80-3 (CANP) - D80-2 (CANN)	Ignition switch off	54 to 69 Ω	Below 54 Ω: Short in line
D80-3 (CANP) - D80-2 (CANN)	Ignition switch off	54 to 69 Ω	Higher than 69 Ω: Open in CAN main bus line
D80-3 (CANP) - D79-4 (BATB)	Ignition switch off	6 kΩ or higher	Below 6 kΩ: +B short
D80-2 (CANN) - D79-4 (BATB)	Ignition switch off	6 kΩ or higher	Below 6 kΩ: +B short
D80-3 (CANP) - D80-4 (GND2)	Ignition switch off	200 Ω or higher	Below 200 Ω: Ground short
D80-2 (CANN) - D80-4 (GND2)	Ignition switch off	200 Ω or higher	Below 200 Ω: Ground short

CHECK CAN BUS WIRE (MAIN BODY ECU - POSITION CONTROL ECU ASSEMBLY) Click here

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

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

Text in Illustration
*a	Front view of wire harness connector (to Main Body ECU [Instrument Panel Junction Block Assembly])	-	-

Note

When disconnecting the cable, some systems need to be initialized after the cable is reconnected Click here.

Disconnect the main body ECU (instrument panel junction block assembly) connectors.

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

Standard Voltage

Tester Connection	Condition	Specified Condition
D79-4 (BATB) - Body ground	Always	11 to 14 V
DH-12 (BECU) - Body ground	Always	11 to 14 V
DF-5 (ACC) - Body ground	Ignition switch ACC	11 to 14 V
DG-1 (ALTB) - Body ground	Always	11 to 14 V
DH-13 (IG) - Body ground	Always	9.5 to 14 V

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

Standard Resistance

Tester Connection	Condition	Specified Condition
DE-17 (GND1) - Body ground	Always	Below 1 Ω
D80-4 (GND2) - Body ground	Always	Below 1 Ω

Result
Result	Proceed to
OK	A
NG (IG terminal)	B
NG (Except IG terminal)	C

REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

GO TO STOP AND START SYSTEM Click here

REPAIR OR REPLACE HARNESS OR CONNECTOR

CHECK CAN BUS WIRE (MAIN BODY ECU - POSITION CONTROL ECU ASSEMBLY)

Text in Illustration
*a	Front view of wire harness connector (to Main Body ECU [Instrument Panel Junction Block Assembly])
*b	Front view of DLC3

Disconnect the main body ECU (instrument panel junction block assembly) connector.

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

Standard Resistance

Tester Connection	Switch Condition	Specified Condition
D80-3 (CANP) - D80-2 (CANN)	Ignition switch off	108 to 132 Ω
D80-3 (CANP) - D8-4 (CG)	Ignition switch off	200 Ω or higher
D80-2 (CANN) - D8-4 (CG)	Ignition switch off	200 Ω or higher
D80-3 (CANP) - D8-16 (BAT)	Ignition switch off	6 kΩ or higher
D80-2 (CANN) - D8-16 (BAT)	Ignition switch off	6 kΩ or higher

REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

CONNECT CONNECTOR
1. Reconnect the D80 main body ECU (instrument panel junction block assembly) connector.
NEXT

CHECK CAN BUS WIRE (POSITION CONTROL ECU ASSEMBLY - MAIN BODY ECU)

Text in Illustration
*A	for LHD
*B	for RHD
*a	Rear view of wire harness connector (to Position Control ECU Assembly)
*b	Front view of DLC3

Disconnect the position control ECU assembly connector.

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

Standard Resistance

for LHD
Tester Connection	Switch Condition	Specified Condition
O26-40 (CANH) - O26-39 (CANL)	Ignition switch off	108 to 132 Ω
O26-40 (CANH) - D8-4 (CG)	Ignition switch off	200 Ω or higher
O26-39 (CANL) - D8-4 (CG)	Ignition switch off	200 Ω or higher
O26-40 (CANH) - D8-16 (BAT)	Ignition switch off	6 kΩ or higher
O26-39 (CANL) - D8-16 (BAT)	Ignition switch off	6 kΩ or higher

for RHD
Tester Connection	Switch Condition	Specified Condition
O16-40 (CANH) - O16-39 (CANL)	Ignition switch off	108 to 132 Ω
O16-40 (CANH) - D8-4 (CG)	Ignition switch off	200 Ω or higher
O16-39 (CANL) - D8-4 (CG)	Ignition switch off	200 Ω or higher
O16-40 (CANH) - D8-16 (BAT)	Ignition switch off	6 kΩ or higher
O16-39 (CANL) - D8-16 (BAT)	Ignition switch off	6 kΩ or higher

REPLACE POSITION CONTROL ECU ASSEMBLY Click here

REPAIR OR REPLACE CAN MAIN WIRE CONNECTOR (POSITION CONTROL ECU ASSEMBLY - MAIN BODY ECU)