DTC U01BD-87: Lost Communication with DC/DC Converter Control Module "C" Missing Message [09/2023 - ]: Procedure

Pre-procedure1

• None.

• Check for DTCs.

  Powertrain > Hybrid Control > Trouble Codes 

  Result

  Result	Proceed to
  Only U01BD-87 is output	A
  U01BD-87 and other DTCs are output	B

Post-procedure1

• Turn the ignition switch off.

Result: 

B 

GO TO DTC CHART (HYBRID CONTROL SYSTEM). Refer to  DIAGNOSTIC TROUBLE CODE CHART [09/2023 - ] 

Result: 

A 

See step  2

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.

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

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

  Standard Voltage

  Tester Connection	Condition	Specified Condition
  1G-1 - Body ground	Ignition switch off	Same as auxiliary battery voltage

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

  *1	AMD Terminal (No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly Side)

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

  Standard Voltage

  Tester Connection	Condition	Specified Condition
  C48-1 (AMD) - Body ground	Ignition switch off	Same as auxiliary battery voltage

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

  *1	AMD Terminal (EV Converter Assembly Side)

  Result

  Proceed to
  OK
  NG

Post-procedure1

• Disconnect the cable from the negative (-) auxiliary battery terminal.

Result: 

NG 

See step  7

Result: 

OK 

See step  3

1. 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.

2. Check that the bolts for the AMD terminal are tightened to the specified torque, the AMD terminal is connected securely, and there are no contact problems.

   Result

   Result		Proceed to
   There are no arc marks.	The terminal is connected securely and there are no contact problems.	A
   There are no arc marks.	The terminal is not connected securely and there is a contact problem.	B
   There are arc marks.	-	C

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *1	AMD Terminal (No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly Side)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *1	AMD Terminal (EV Converter Assembly Side)

Result: 

B 

CONNECT SECURELY 

Result: 

C 

REPLACE MALFUNCTIONING PARTS 

Result: 

A 

See step  4

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 EV converter assembly connector.

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

• Connect the cable to the negative (-) auxiliary battery terminal.
• Turn the ignition switch to ON.

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

  Standard Voltage

  Tester Connection	Condition	Specified Condition
  C47-3 (IGCT) - Body ground	Ignition switch ON	Same as auxiliary battery voltage

  NOTE:

  Turning the ignition switch to ON with the EV converter assembly removed causes other DTCs to be stored. Clear the DTCs after performing this inspection.

  HINT: 

  As there might be an intermittent malfunction, inspect the following items even if the measured voltage is as specified.

  • Installation condition of fuse(s) (before removing fuse(s)) (IGCT circuit)
  • Fuse condition (before and after removing fuse(s)) (IGCT circuit)
  • Connection condition of connectors (IGCT circuit)
  • Wire harness condition (IGCT circuit)
  • Wire harness condition (GND circuit)

  Result

  Proceed to
  OK
  NG

Post-procedure1

• Turn the ignition switch off.
• Disconnect the cable from the negative (-) auxiliary battery terminal.
• Reconnect the EV converter assembly connector.

Result: 

NG 

See step  6

Result: 

OK 

See step  5

Refer to PROCEDURE - Step 1

Result

Result: 

OK 

GO TO CAN COMMUNICATION SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [09/2023 - ] 

Result: 

NG 

CONNECT SECURELY 

Pre-procedure1

• Remove the IGCT NO. 1 relay from the No. 1 engine room relay block and No. 1 junction block assembly.
• Disconnect the EV converter assembly connector.

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

  Standard Resistance (Check for Open)

  Tester Connection	Condition	Specified Condition	Result
  C47-3 (IGCT) - 5 (IGCT NO. 1 relay holder)	Ignition switch off	Below 1 Ω	Ω

  Standard Resistance (Check for Short)

  Tester Connection	Condition	Specified Condition	Result
  C47-3 (IGCT) or 5 (IGCT NO. 1 relay holder) - Body ground and other terminals	Ignition switch off	10 kΩ or higher	kΩ

  Result

  Proceed to
  OK
  NG

Post-procedure1

• Install the IGCT NO. 1 relay.
• Reconnect the hybrid vehicle control ECU assembly connector.

Result: 

OK 

REPAIR OR REPLACE ECU POWER SOURCE CIRCUIT. Refer to  ECU Power Source Circuit [09/2023 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

1. 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.

2. Check that the bolts for the AMD terminal are tightened to the specified torque, the AMD terminal is connected securely, and there are no contact problems.

   Result

   Result		Proceed to
   There are no arc marks.	The terminal is connected securely and there are no contact problems.	A
   There are no arc marks.	The terminal is not connected securely and there is a contact problem.	B
   There are arc marks.	-	C

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *1	AMD Terminal (No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly Side)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *1	AMD Terminal (EV Converter Assembly Side)

Result: 

B 

CONNECT SECURELY 

Result: 

C 

REPLACE MALFUNCTIONING PARTS 

Result: 

A 

See step  8

Pre-procedure1

• Disconnect the AMD connector from the No. 1 engine room relay block and No. 1 junction block assembly.

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

  *1	AMD Terminal (No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly Side)

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

  Standard Resistance

  Tester Connection	Condition	Specified Condition	Result
  C48-1 (AMD) or 1G-1 - Body ground and other terminals	Ignition switch off	10 kΩ or higher	kΩ

  Result

  Proceed to
  OK
  NG

Post-procedure1

• Reconnect the AMD connector.

Result: 

NG 

See step  10

Result: 

OK 

See step  9

Pre-procedure1

• Check the fusible link block assembly (DC/DC) for improper installation.

  OK

  The fusible link block assembly is installed securely.

• Remove the fusible link block assembly from the No. 1 engine room relay block and No. 1 junction block assembly.

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

  Standard Resistance

  Tester Connection	Condition	Specified Condition	Result
  1G-1 - 1A-1	Always	Below 1 Ω	Ω

  Result

  Proceed to
  OK
  NG

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

  *1	Fusible Link Block Assembly

Post-procedure1

• Install the fusible link block assembly.

Result: 

OK 

REPAIR OR REPLACE HARNESS OR CONNECTOR (AUXILIARY BATTERY - NO. 1 ENGINE ROOM RELAY BLOCK AND NO. 1 JUNCTION BLOCK ASSEMBLY) 

Result: 

NG 

REPLACE FUSIBLE LINK BLOCK ASSEMBLY (DC/DC) 

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 AMD connector from the EV converter assembly.

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

  *1	AMD Terminal (EV Converter Assembly Side)

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

  Standard Resistance

  Tester Connection	Condition	Specified Condition	Result
  C48-1 (AMD) - Body ground and other terminals	Ignition switch off	10 MΩ or higher	MΩ

  Result

  Proceed to
  OK
  NG

Post-procedure1

• Connect the AMD connector from the EV converter assembly.

Result: 

NG 

See step  12

Result: 

OK 

See step  11

Pre-procedure1

• Check the fusible link block assembly (DC/DC) for improper installation.

  OK

  The fusible link block assembly is installed securely.

• Remove the fusible link block assembly from the No. 1 engine room relay block and No. 1 junction block assembly.

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

  Standard Resistance

  Tester Connection	Condition	Specified Condition	Result
  1G-1 - 1A-1	Always	Below 1 Ω	Ω

  Result

  Proceed to
  OK
  NG

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

  *1	Fusible Link Block Assembly

Post-procedure1

• Install the fusible link block assembly.

Result: 

OK 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

NG 

REPLACE FUSIBLE LINK BLOCK ASSEMBLY (DC/DC) 

Pre-procedure1

• Check the fusible link block assembly (DC/DC) for improper installation.

  OK

  The fusible link block assembly is installed securely.

• Remove the fusible link block assembly from the No. 1 engine room relay block and No. 1 junction block assembly.

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

  Standard Resistance

  Tester Connection	Condition	Specified Condition	Result
  1G-1 - 1A-1	Always	Below 1 Ω	Ω

  Result

  Proceed to
  OK
  NG

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

  *1	Fusible Link Block Assembly

Post-procedure1

• Install the fusible link block assembly.

Result: 

OK 

REPLACE EV CONVERTER ASSEMBLY. Refer to  REMOVAL [09/2023 - ] 

Result: 

NG 

See step  13

Result

Result: 

NEXT 

REPLACE EV CONVERTER ASSEMBLY. Refer to  REMOVAL [09/2023 - ]