Toyota Tundra Service Manual: Lost Communication with "Seat Control Module A" (U0208)

DESCRIPTION

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.

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• Before measuring the resistance of the CAN bus, turn the ignition switch off and leave the vehicle for 1 minute or more without operating the key, 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 battery terminal. Therefore, make sure to read the disconnecting the cable from the battery terminal notice before proceeding with work.

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

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• 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, 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 CAN Bus Check and check that all the ECUs and sensors connected to the CAN communication system are displayed as normal.

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

HINT:

• Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.
• Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.

PROCEDURE

(a) Reconfirm DTCs.

HINT:

If DTC U1002 is output from Gateway 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.

B

GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC

A

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

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

*a Front view of wire harness connector (to Front Power Seat Switch LH [Power Seat Control ECU])

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

Standard Resistance:

NG

REPAIR OR REPLACE FRONT POWER SEAT SWITCH LH CAN BRANCH WIRE OR CONNECTOR

OK

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

*a Front view of wire harness connector (to Front Power Seat Switch [Power Seat Control ECU])

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

Standard Resistance:

(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.

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

Standard Voltage:

OK

REPLACE FRONT POWER SEAT SWITCH LH (POWER SEAT CONTROL ECU)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)