Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Inspection Procedure
- Before inspecting the high-voltage system, take safety precautions to prevent electrical shocks, such as wearing insulated gloves and removing the service plug grip. After removing the service plug grip, put it in your pocket to prevent other technicians from reconnecting it while you are servicing the high-voltage system.
- After disconnecting the service plug grip, wait for at least 5 minutes before touching any of the high-voltage connectors or terminals.
HINT:
At least 5 minutes is required to discharge the high-voltage condenser inside the inverter.
- READ OUTPUT DTC (HV ECU)
- Connect the hand-held tester to the DLC3.
- Turn the power switch ON (IG).
- Turn the hand-held tester ON.
- On the hand-held tester, enter the following menus: DIAGNOSIS / OBD/MOBD / HV ECU / DTC INFO /CURRENT CODES.
- Read DTCs.
- Result: DTC listed in the table below is output
DTC TROUBLEDTC No. INF Code Detection Item P0A94 551 or 552 DC/DC Converter Malfunction
YES: GO TO THE DTC TEST SHOWN IN THE TABLE ABOVE
NO: Go to Next Step
- CHECK CONNECTION CONDITION OF INVERTER CONNECTOR (LOOSENESS AND POOR CONTACT) CAUTION: Wear insulated gloves before performing the following operation.
- Turn the power switch OFF.
- Remove the service plug grip (see SERVICE PLUG GRIP
).NOTE: Turning the power switch ON (READY) with the service plug grip removed could cause malfunction. Therefore, never turn the power switch ON (READY) in this state.
- Remove the inverter cover (see W/CONVERTER INVERTER ASSY in HYBRID CONTROL SYSTEM ).
- Check the connection condition of the I9 and I10 inverter connectors.
- OK: Connectors have been connected securely and there is no poor connection.
- Reinstall the inverter cover (see W/CONVERTER INVERTER ASSY in HYBRID CONTROL SYSTEM ).
- Reinstall the service plug grip (see SERVICE PLUG GRIP ).
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
NG: CONNECT SECURELY
OK: Go to Next Step
- READ OUTPUT DTC (HV ECU)
- Connect the hand-held tester to the DLC3.
- Turn the power switch ON (IG).
HINT:
DTCs for the interlock switch system are output when turning the power switch ON (IG) with both service plug grip and inverter cover removed.
- Turn the hand-held tester ON.
- On the hand-held tester, enter the following menus: DIAGNOSIS / OBD/MOBD / HV ECU / DTC INFO /CURRENT CODES.
- Read DTCs.
- Result: DTCs P0A78 (INF 282, 286) and P0A7A (INF 324) (inverter circuit malfunction) are output
NO: REPLACE W/CONVERTER INVERTER ASSY (See W/CONVERTER INVERTER ASSY in HYBRID CONTROL SYSTEM )
YE: Go to Next Step
- INSPECT W/CONVERTER INVERTER ASSY (IGCT VOLTAGE) CAUTION: Wear insulated gloves before performing the following operation.
- Turn the power switch OFF.
- Remove the service plug grip (see SERVICE PLUG GRIP
).NOTE: Turning the power switch ON (READY) with the service plug grip removed could cause malfunction. Therefore, never turn the power switch ON (READY) in this state.
- Remove the inverter cover (see W/CONVERTER INVERTER ASSY in HYBRID CONTROL SYSTEM ).
- Turn the power switch ON (IG).
HINT:
DTCs for the interlock switch system are output when turning the power switch ON (IG) with both service plug grip and inverter cover removed.
- Measure the voltage between the terminals of the inverter connector.
- Standard:
VOLTAGE CHECKTester Connection Specified Condition IGCT (I9-1) - GND1 (I9-2) 8 V or more - Turn the power switch OFF.
- Reinstall the inverter cover (see W/CONVERTER INVERTER ASSY in HYBRID CONTROL SYSTEM ).
- Reinstall the service plug grip (see SERVICE PLUG GRIP ).
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
OK: REPLACE W/CONVERTER INVERTER ASSY (See W/CONVERTER INVERTER ASSY in HYBRID CONTROL SYSTEM )
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.