DTC P0A08-12: DC/DC Converter Status Circuit Short to Battery [12/2023 - ]: Procedure

Pre-procedure1

• Turn the ignition switch to ON.

• Connect an oscilloscope between the hybrid vehicle control ECU assembly terminals specified in the table below, and measure the waveform.

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

  *a

  Component with harness connected (Hybrid Vehicle Control ECU Assembly)

  -

  -

  Item	Content
  Terminal	B88-35 (VLO) - D117-1 (E1)
  Equipment Setting	5 V/DIV., 50 ms./DIV.
  Condition	Ignition switch ON

  OK

  The waveform appears as shown in the illustration.

  HINT: 

  • Perform this inspection with the hybrid vehicle control ECU assembly connector connected.
  • The waveform (duty ratio) differs depending on the command value from the hybrid vehicle control ECU assembly.

  Result

  Proceed to
  OK
  NG

Post-procedure1

• Turn the ignition switch off.

Result: 

NG 

See step  4

Result: 

OK 

See step  2

See step  3

Result

Result: 

NEXT 

See step  3

Pre-procedure1

• None.

• Check for DTCs.

  Powertrain > Hybrid Control > Trouble Codes 

  Result

  Result	Proceed to
  P0A08-12 is not output	A
  P0A08-12 is output	B

Post-procedure1

• Turn the ignition switch off.

Result: 

A 

USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [09/2023 - ] 

Result: 

B 

REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY. Refer to  REMOVAL [12/2023 - ] 

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 DC/DC converter assembly connector.

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

• Disconnect the hybrid vehicle control ECU assembly connector.
• 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.

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

  *a

  Front view of wire harness connector (to DC/DC Converter Assembly)

  *b

  Front view of wire harness connector (to Hybrid Vehicle Control ECU Assembly)

  Standard Voltage

  Tester Connection	Condition	Specified Condition	Result
  I49-6 (VLO) or B88-35 (VLO) - Body ground and other terminals	Ignition switch ON	Below 1 V	V

  NOTE:

  Turning the ignition switch to ON with the DC/DC converter assembly connector and the hybrid vehicle control ECU assembly connector disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

  Result

  Proceed to
  OK
  NG

Post-procedure1

• Turn the ignition switch off.
• Disconnect the cable from the negative (-) auxiliary battery terminal.
• Reconnect the hybrid vehicle control ECU assembly connector.
• Reconnect the DC/DC converter assembly connector.

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  5

HINT: 

Refer to REMOVAL [12/2023 - ]

Result

Result: 

NEXT 

See step  6

See step  3

Result

Result: 

NEXT 

See step  7

Pre-procedure1

• None.

• Check for DTCs.

  Powertrain > Hybrid Control > Trouble Codes 

  Result

  Result	Proceed to
  P0A08-12 is not output	A
  P0A08-12 is output	B

Post-procedure1

• Turn the ignition switch off.

Result: 

A 

COMPLETED 

Result: 

B 

REPLACE DC/DC CONVERTER ASSEMBLY. Refer to  REMOVAL [12/2023 - ]