DTC P0A78-202: Drive Motor "A" Inverter Performance [08/2013 - ]: Procedure

WARNING: This page is about a different car, the 2014 Lexus ES 300h. However, it is still accessible from the selected car via links, so may be relevant.

CHECK HYBRID VEHICLE TRANSAXLE ASSEMBLY (MG2) See step 12
NG → See step 4

OK: Go to next step
REPLACE INVERTER WITH CONVERTER ASSEMBLY
Refer to COMPONENTS [08/2013 - ]

NEXT: Go to next step

CHECK DTC OUTPUT (HYBRID CONTROL)

Check the other DTCs that were output together with DTC P0A78-202.

Result

DTC No.	Relevant Diagnosis
P0A78-113, 128, 284, 286, 287, 505, 506, 806, 807, 808	Drive Motor "A" Inverter Performance

NOTE:

DTC P0A78-202 is stored after any of DTCs P0A78-113, 128, 284, 286, 287, 505, 506, 806, 807 and 808 are stored. After troubleshooting and repairing the malfunction which caused DTC P0A7A-202 to be stored be sure to troubleshoot all the other DTCs.

NEXT → See step 16

CHECK MOTOR CABLE See step 29
NG → See step 8

OK: Go to next step
REPLACE HYBRID VEHICLE TRANSAXLE ASSEMBLY
Refer to COMPONENTS [08/2013 - ]

NEXT: Go to next step
REPLACE INVERTER WITH CONVERTER ASSEMBLY
Refer to COMPONENTS [08/2013 - ]

NEXT: Go to next step

CHECK DTC OUTPUT (HYBRID CONTROL)

Check the other DTCs that were output together with DTC P0A78-202.

Result

DTC No.	Relevant Diagnosis
P0A78-113, 128, 284, 286, 287, 505, 506, 806, 807, 808	Drive Motor "A" Inverter Performance

NOTE:

NEXT → See step 16

CHECK HYBRID VEHICLE TRANSAXLE ASSEMBLY (MG2)

WARNING:

Be sure to wear insulated gloves.

Check that the service plug grip is not installed.
NOTE:
After removing the service plug grip, do not turn the power switch on (READY), unless instructed by the service information because this may cause a malfunction.
Disconnect the motor cable from the hybrid vehicle transaxle assembly.

Check MG2 for an interphase short using a milliohmmeter.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Using a milliohmmeter, measure the resistance according to the value(s) in the table below.

HINT:

If the MG2 temperature is high, the resistance will vary greatly from the specification. Therefore, measure the resistance at least 8 hours after the vehicle is stopped.

Standard Resistance

Tester Connection	Condition	Specified Condition
d2-1 (U) - d2-2 (V)	Power switch off	69.5 to 76.5 mΩ
d2-2 (V) - d2-3 (W)	Power switch off	66.5 to 73.5 mΩ
d2-3 (W) - d2-1 (U)	Power switch off	66.5 to 73.5 mΩ

TEXT IN ILLUSTRATION

*a	Component without motor cable connected (Hybrid Vehicle Transaxle Assembly)

HINT:

To correct the variation of the measured resistance due to temperature, use the following formula to calculate the resistance at 20°C (68° F).

R20 = Rt / {1 + 0.00393 X (T - 20)}

The calculation is based on the following:

R20: Resistance at 20°C (68° F) (mΩ)
Rt: Measured resistance (mΩ)
T: Temperature when the resistance is measured (° C)

Using a megohmmeter set to 500 V, measure the resistance according to the value(s) in the table below.

NOTE:

Be sure to set the megohmmeter to 500 V when performing this test. Using a setting higher than 500 V can result in damage to the component being inspected.

Standard Resistance

Tester Connection	Condition	Specified Condition
d2-1 (U) - Body ground	Power switch off	100 MΩ or higher
d2-2 (V) - Body ground	Power switch off	100 MΩ or higher
d2-3 (W) - Body ground	Power switch off	100 MΩ or higher

Connect the motor cable.

NG → See step 12

OK: Go to next step

REPLACE MOTOR CABLE
Refer to COMPONENTS [08/2013 - ]

NEXT: Go to next step
REPLACE INVERTER WITH CONVERTER ASSEMBLY
Refer to COMPONENTS [08/2013 - ]

NEXT: Go to next step

CHECK DTC OUTPUT (HYBRID CONTROL)

Check the other DTCs that were output together with DTC P0A78-202.

Result

DTC No.	Relevant Diagnosis
P0A78-113, 128, 284, 286, 287, 505, 506, 806, 807, 808	Drive Motor "A" Inverter Performance

NOTE:

NEXT → See step 16

REPLACE MOTOR CABLE
Refer to COMPONENTS [08/2013 - ]

NEXT: Go to next step
REPLACE HYBRID VEHICLE TRANSAXLE ASSEMBLY
Refer to COMPONENTS [08/2013 - ]

NEXT: Go to next step
REPLACE INVERTER WITH CONVERTER ASSEMBLY
Refer to COMPONENTS [08/2013 - ]

NEXT: Go to next step

CHECK DTC OUTPUT (HYBRID CONTROL)

Check the other DTCs that were output together with DTC P0A78-202.

Result

DTC No.	Relevant Diagnosis
P0A78-113, 128, 284, 286, 287, 505, 506, 806, 807, 808	Drive Motor "A" Inverter Performance

NOTE:

NEXT → See step 16

GO TO DTC CHART (HYBRID CONTROL SYSTEM). Refer to DIAGNOSTIC TROUBLE CODE CHART [08/2013 - ]