DTC U11BF-87: Lost Communication with TCM (ch5) Missing Message [09/2023 - ]: Procedure

WARNING: This page is about a different car, the 2024 Lexus TX 500h. However, it is still accessible from the selected car via links, so may be relevant.

CHECK CAN BUS MAIN WIRE

WARNING:

Be sure to wear insulated gloves.

Pre-procedure1

Check that the service plug grip is not installed.
NOTE:
After removing the service plug grip, do not turn the ignition switch to ON (READY), unless instructed by the service information because this may cause a malfunction.
Disconnect the cable to the negative (-) auxiliary battery terminal.
Disconnect the hybrid motor control inverter assembly connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition	Result
C46-36 (CALH) - C46-37 (CALL)	Disconnect the cable to the negative (-) auxiliary battery terminal	108 to 132 Ω	Ω
C46-36 (CALH) or C46-37 (CALL) - Other power source terminals	Disconnect the cable to the negative (-) auxiliary battery terminal	6 kΩ or higher	kΩ
C46-36 (CALH) or C46-37 (CALL) - Other terminals and body ground	Disconnect the cable to the negative (-) auxiliary battery terminal	200 kΩ or higher	kΩ

Result

Proceed to
OK
NG

Post-procedure1

Reconnect the hybrid motor control inverter assembly connector.
Reconnect the cable to the negative (-) auxiliary battery terminal.

Result:

See step 7

Result:

See step 2

CHECK HARNESS AND CONNECTOR (NO. 1 ENGINE ROOM RELAY BLOCK AND NO. 1 JUNCTION BLOCK ASSEMBLY - TCM)
HINT:

Refer to PROCEDURE - Step 2

Result

Proceed to

OK

NG

Result:

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

Result:

OK

See step 3
CHECK HARNESS AND CONNECTOR (TCM - BODY GROUND)
HINT:

Refer to PROCEDURE - Step 1

Result

Proceed to

OK

NG

Result:

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

Result:

OK

See step 4
REPLACE TCM
HINT:

Refer to REMOVAL [09/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 5

CLEAR DTC

Clear the DTCs.

Powertrain > Motor Generator > Clear DTCs

Result

Proceed to
NEXT

Result:

See step 6

DTC OUTPUT (MOTOR GENERATOR)

Pre-procedure1

Turn the ignition switch to ON and wait for 2 minutes or more.

Check for DTCs.

Powertrain > Motor Generator > Trouble Codes

Result

Result	Proceed to
U11BF-87 is output	A
U11BF-87 is not output	B

Post-procedure1

Turn the ignition switch off.

Result:

REPLACE HYBRID MOTOR CONTROL INVERTER ASSEMBLY. Refer to REMOVAL [09/2023 - ]

Result:

END

CHECK HARNESS AND CONNECTOR (HYBRID MOTOR CONTROL INVERTER ASSEMBLY - TCM)

WARNING:

Be sure to wear insulated gloves.

Pre-procedure1

Check that the service plug grip is not installed.
NOTE:
After removing the service plug grip, do not turn the ignition switch to ON (READY), unless instructed by the service information because this may cause a malfunction.
Disconnect the hybrid motor control inverter assembly connector.
Disconnect the TCM connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition	Result
C46-36 (CALH) - C25-31 (CANI)	Ignition switch off	Below 1 Ω	Ω
C46-37 (CALL) - C25-32 (CANO)	Ignition switch off	Below 1 Ω	Ω
C46-36 (CALH) or C25-31 (CANI) - Other power source terminals	Ignition switch off	10 kΩ or higher	kΩ
C46-37 (CALL) or C25-32 (CANO) - Other terminals and body ground	Ignition switch off	10 kΩ or higher	kΩ

Result

Proceed to
OK
NG

Post-procedure1

Reconnect the TCM connector.
Reconnect the hybrid motor control inverter assembly connector.

Result:

REPLACE TCM. Refer to REMOVAL [09/2023 - ]

Result:

REPAIR OR REPLACE HARNESS OR CONNECTOR (ML-BUS)