DTC P0A08-12: DC/DC Converter Status Circuit Short to Battery [08/2023 - ]: Procedure

Pre-procedure1

• Turn the ignition switch to ON.

• Connect an oscilloscope between the hybrid vehicle control ECU 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)

  -

  -

  Item	Content
  Terminal	A21-35 (VLO) - C59-1 (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 connector connected.
  • The waveform (duty ratio) differs depending on the command value from the hybrid vehicle control ECU.

  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 [10/2022 - ] 

Result: 

B 

REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY. Refer to  REMOVAL [10/2022 - ] 

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 appropriate 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 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)

  Standard Voltage

  Tester Connection	Condition	Specified Condition	Result
  H5-6 (VLO) or A21-35 (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 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 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 [10/2022 - ]

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 [08/2023 - ]