Last Modified: 04-05-2023 6.11:8.1.0 Doc ID: RM1000000018DL1
Model Year Start: 2018 Model: Sienna Prod Date Range: [11/2017 - 08/2018]
Title: NETWORKING: CAN COMMUNICATION SYSTEM: U0208; Lost Communication with "Seat Control Module A"; 2018 MY Sienna [11/2017 - 08/2018]

DTC

U0208

Lost Communication with "Seat Control Module A"

DESCRIPTION

DTC Code

DTC Detection Condition

Trouble Area

U0208

There is no communication from the position control ECU and switch.
  • Power source circuit of front power seat switch LH
  • Front power seat switch LH
  • Front power seat switch LH branch wire or connector

HINT:

For vehicle with seat position memory system only.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

NOTICE:

  • Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output.

    Click here 2018 - 2020 MY Sienna [11/2017 -        ]; NETWORKING: CAN COMMUNICATION SYSTEM: HOW TO PROCEED WITH TROUBLESHOOTING

  • Before measuring the resistance of the CAN bus, turn the engine switch off and leave the vehicle for 1 minute or more without operating the key or any switches, or opening or closing the doors. After that, disconnect the cable from the negative (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
  • After turning the ignition switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work.

    Click here 2017 - 2020 MY Sienna [08/2016 -        ]; INTRODUCTION: REPAIR INSTRUCTION: PRECAUTION

  • Some parts must be initialized and set when replacing or removing and installing parts.

    Click here 2018 - 2020 MY Sienna [11/2017 -        ]; INTRODUCTION: REPAIR INSTRUCTION: INITIALIZATION

  • After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.

    DTC check procedure: Turn the ignition switch to ON and wait for 1 minute or more. Then operate the suspected malfunctioning system and drive the vehicle at 60 km/h (37 mph) or more for 5 minutes or more.

  • After the repair, perform the CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed as normal.

    Click here 2018 MY Sienna [11/2017 - 08/2018]; NETWORKING: CAN COMMUNICATION SYSTEM: DIAGNOSIS SYSTEM

  • Inspect the fuses for circuits related to this system before performing the following procedure.

HINT:

  • Before disconnecting related connectors for inspection, push in on each connector body to check that the connector is not loose or disconnected.
  • When a connector is disconnected, check that the terminals and connector body are not cracked, deformed or corroded.

PROCEDURE

1.

RECONFIRM DTC OUTPUT

(a) Reconfirm DTCs.

HINT:

If DTC U1002 is output from Main Body of the main body ECU (multiplex network body ECU), this indicates a sub bus 1 malfunction. Troubleshoot for DTC U1002 and check for malfunctions in sub bus 1.

Result

Proceed to

DTC U1002 is not output from main body ECU (multiplex network body ECU) (Techstream display: Main Body)

A

DTC U1002 is output from main body ECU (multiplex network body ECU) (Techstream display: Main Body)

B
B

GO TO CIRCUITS INDICATED BY OUTPUT DTCS

A

2.

CHECK FOR OPEN IN CAN BUS WIRE (FRONT POWER SEAT SWITCH LH BRANCH WIRE)

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

(b) Disconnect the front power seat switch LH connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

Y9-8 - Y9-7

Cable disconnected from negative (-) battery terminal

54 to 69 Ω

Text in Illustration

*a

Front view of wire harness connector

(to Front Power Seat Switch LH)
NG

REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR
OK

3.

CHECK HARNESS AND CONNECTOR (FRONT POWER SEAT SWITCH LH - POWER SOURCE)

(a) Disconnect the front power seat switch LH connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

Y8-2 - Body ground

Cable disconnected from negative (-) battery terminal

Below 1 Ω

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

NOTICE:

When disconnecting the cable, some systems need to be initialized after the cable is reconnected (See page 2018 - 2020 MY Sienna [11/2017 -        ]; INTRODUCTION: REPAIR INSTRUCTION: INITIALIZATION )

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

Y8-7 - Body ground

Always

11 to 14 V

Text in Illustration

*a

Front view of wire harness connector

(to Front Power Seat Switch LH)
OK

REPLACE FRONT POWER SEAT SWITCH LH

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR