DTC P0A78-113: Drive Motor "A" Inverter Performance: Procedure

CHECK DTC OUTPUT (EV)

Connect the Techstream to the DLC3.
Turn the power switch on (IG).
Enter the following menus: Powertrain / EV / Trouble Codes.

Check if DTCs related to the EV control system are output.

Result

Result	Proceed to
P0A78-202 is not output.	A
P0A78-202 is also output.	B

NOTE:

If P0A78-202 is output, troubleshoot it first. After completing the troubleshooting for P0A78-202, return to perform troubleshooting for this DTC.
Parts repaired or replaced during troubleshooting for P0A78-202 do not need to be re-inspected in this diagnosis procedure.

Turn the power switch off.

B → See step 23

A: Go to next step

CHECK DTC OUTPUT (EV)

Connect the Techstream to the DLC3.
Turn the power switch on (IG).
Enter the following menus: Powertrain / EV / Trouble Codes.

Check if DTCs related to the EV control system are output.

HINT:

If P0A78-202 was not output in step 1 of this diagnosis procedure, check Table 1 below.
If P0A78-202 was output in step 1 of this diagnosis procedure, repair that DTC first, then check Table 2 below.

Result

Result	Proceed to
Only P0A78-113 is output, or DTCs other than the ones in the table below are also output.	A
Any of the following DTCs including pending DTCs are also output.	B

TABLE 1

DTC No.	Relevant Diagnosis
P0A1A (all INF codes)*1	Generator Control Module
P0A1B (all INF codes)*1	Drive Motor "A" Control Module
P0A1D (all INF codes)*1	EV Control Module
P0A3F-243	Drive Motor "A" Position Sensor Circuit
P0A40-500	Drive Motor "A" Position Sensor Circuit Range/Performance
P0A41-245	Drive Motor "A" Position Sensor Circuit Low
P0A60 (all INF codes)*1	Drive Motor "A" Phase V Current
P0A63 (all INF codes)*1	Drive Motor "A" Phase W Current
P0A78-266, 267, 287, 306, 505, 506, 586, 806, 807, 808	Drive Motor "A" Inverter Performance
P0A90-509	Drive Motor "A" Performance
P0A94-585, 587, 589, 590	Inverter Performance
P0ADB-227	EV Battery No. 1 Positive Contactor Control Circuit Low
P0ADC-226	EV Battery No. 1 Positive Contactor Control Circuit High
P0ADF-229	EV Battery Negative Contactor Control Circuit Low
P0AE0-228	EV Battery Negative Contactor Control Circuit High
P0C76-523	EV Battery System Discharge Time Too Long
P3004-803	High Voltage Power Resource
P3322-368	EV Battery No. 2 Positive Contactor Control Circuit Low
P3323-367	EV Battery No. 2 Positive Contactor Control Circuit High

TABLE 2

DTC No.	Relevant Diagnosis
P0A1A (all INF codes)*1	Generator Control Module
P0A1B (all INF codes)*1	Drive Motor "A" Control Module
P0A1D (all INF codes)*1	EV Control Module
P0A3F-243	Drive Motor "A" Position Sensor Circuit
P0A40-500	Drive Motor "A" Position Sensor Circuit Range/Performance
P0A41-245	Drive Motor "A" Position Sensor Circuit Low
P0A60-294	Drive Motor "A" Phase V Current
P0A63-302	Drive Motor "A" Phase W Current
P0A78-266, 267, 287, 306, 505, 506, 586, 806, 807, 808	Drive Motor "A" Inverter Performance
P0A94-585, 587, 589, 590	Inverter Performance
P0ADB-227	EV Battery No. 1 Positive Contactor Control Circuit Low
P0ADC-226	EV Battery No. 1 Positive Contactor Control Circuit High
P0ADF-229	EV Battery Negative Contactor Control Circuit Low
P0AE0-228	EV Battery Negative Contactor Control Circuit High
P0C76-523	EV Battery System Discharge Time Too Long
P3004-803	High Voltage Power Resource
P3322-368	EV Battery No. 2 Positive Contactor Control Circuit Low
P3323-367	EV Battery No. 2 Positive Contactor Control Circuit High

HINT:

*1: If any INF codes are output for this DTC, refer to the corresponding diagnostic procedure.
P0A78-113 may be set due to a malfunction which also causes DTCs in the preceding table to be set. In this case, first troubleshoot the output DTCs in the preceding table. Then, perform a test to attempt to reproduce the problems, and check that no DTCs are output.

Turn the power switch off.

B → See step 22

A: Go to next step

CHECK CONNECTOR CONNECTION CONDITION (INVERTER WITH CONVERTER ASSEMBLY CONNECTOR) See step 7
NG → CONNECT SECURELY

OK: Go to next step
CHECK HARNESS AND CONNECTOR (INVERTER WITH CONVERTER ASSEMBLY - MOTOR RESOLVER) See step 3
NG → REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to next step
CHECK MOTOR RESOLVER See step 4
NG → See step 13

OK: Go to next step

CHECK INVERTER WITH CONVERTER ASSEMBLY (MOTOR CABLE CONNECTION CONDITION)

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 repair information because this may cause a malfunction.
Remove the upper inverter cover sub-assembly from the inverter with converter assembly.

Fig 1: Identifying Upper Inverter Cover Sub-Assembly Bolts
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Check that the bolts for the motor cable are tightened to the specified torque, the motor cable is connected securely, and there are no contact problems.

Fig 2: Identifying Motor Cable Bolts
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Specified Condition

Bolt A

8.0 N*m (82 kgf*cm, 71 in.*lbf)

Bolt B

9.2 N*m (94 kgf*cm, 81 in.*lbf)
NOTE:
- Make sure that the tightening torque of the bolt A is between 6.4 and 9.6 N*m (65 and 98 kgf*cm, 57 and 85 in.*lbf).
- Make sure that the tightening torque of the bolt B is between 6.4 and 12 N*m (65 and 122 kgf*cm, 57 and 106 in.*lbf).
Disconnect the motor cable from the inverter with converter assembly.

Check for arc marks at the bolts and terminals for the motor cable.

Result

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

Connect the motor cable to the inverter with converter assembly.
Install the upper inverter cover sub-assembly to the inverter with converter assembly.

B → REPLACE MALFUNCTIONING PARTS

C → CONNECT SECURELY

A: Go to next step

CHECK EV TRANSAXLE WITH MOTOR 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 repair information because this may cause a malfunction.
Remove the upper inverter cover sub-assembly from the inverter with converter assembly.

Fig 3: Identifying Upper Inverter Cover Sub-Assembly Bolts
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Disconnect the motor cable from the inverter with converter assembly.

Check MG2 for an interphase short using a milliohmmeter.

Fig 4: Measuring Resistance Of Motor Cable (Inverter With Converter Assembly Side) Connector

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	Switch Condition	Specified Condition
U2-1 (W) - U2-2 (U)	Power switch off	46.1 to 51.2 mΩ
U2-2 (U) - U2-3 (V)	Power switch off	46.5 to 51.5 mΩ
U2-3 (V) - U2-1 (W)	Power switch off	46.2 to 51.2 mΩ

TEXT IN ILLUSTRATION

*1	Motor Cable (Inverter with Converter Assembly Side)
*2	Shield Ground

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 insulation 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	Switch Condition	Specified Condition
U2-1 (W) - Body ground and shield ground	Power switch off	100 MΩ or higher
U2-2 (U) - Body ground and shield ground	Power switch off	100 MΩ or higher
U2-3 (V) - Body ground and shield ground	Power switch off	100 MΩ or higher

Connect the motor cable to the inverter with converter assembly.
Install the upper inverter cover sub-assembly to the inverter with converter assembly.

NG → See step 18

OK: Go to next step

CHECK FUSE (PCU)

Remove the PCU fuse from the No. 2 motor compartment relay block.

Fig 5: Identifying PCU Fuse On No. 2 Motor Compartment Relay Block
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

Standard Resistance

Tester Connection	Switch Condition	Specified Condition
PCU fuse	Always	Below 1 Ω

TEXT IN ILLUSTRATION

*1	No. 2 Motor Compartment Relay Block
*2	PCU Fuse

Install the PCU fuse.

NG → See step 15

OK: Go to next step

CHECK HARNESS AND CONNECTOR (INVERTER WITH CONVERTER ASSEMBLY POWER SOURCE CIRCUIT)

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 repair information because this may cause a malfunction.
Disconnect the inverter with converter assembly connector.

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

Fig 6: Measuring Resistance Of Inverter With Converter Assembly Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Standard Resistance

Tester Connection	Switch Condition	Specified Condition
A21-28 (GND1) - Body ground	Power switch off	Below 1 Ω
A21-27 (GND2) - Body ground	Power switch off	Below 1 Ω

TEXT IN ILLUSTRATION

*a	Front view of wire harness connector (to Inverter with Converter Assembly)

Connect the cable to the negative (-) auxiliary battery terminal.
Turn the power switch on (IG).

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

Standard Voltage

Tester Connection	Switch Condition	Specified Condition
A21-10 (+B) - Body ground	Power switch on (IG)	11 to 14 V
A21-9 (+B2) - Body ground	Power switch on (IG)	11 to 14 V

NOTE:

Turning the power switch on (IG) with the inverter with converter assembly connector disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

Turn the power switch off.
Disconnect the cable from the negative (-) auxiliary battery terminal.
Reconnect the inverter with converter assembly connector.

NG → REPAIR OR REPLACE POWER SOURCE CIRCUIT

OK: Go to next step

CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU - INVERTER WITH CONVERTER ASSEMBLY)

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 repair information because this may cause a malfunction.
Disconnect the inverter with converter assembly connector.
Disconnect the power management control ECU connector.

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

Fig 7: Measuring Resistance Of Power Management Control ECU - Inverter With Converter Assembly Harness & Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

TEXT IN ILLUSTRATION

Front view of wire harness connector
(to Inverter with Converter Assembly)

Rear view of wire harness connector
(to Power Management Control ECU)

Standard Resistance (Check for Open)

Tester Connection	Switch Condition	Specified Condition
A23-5 (HTM+) - A21-8 (HTM+)	Power switch off	Below 1 Ω
A23-4 (HTM-) - A21-18 (HTM-)	Power switch off	Below 1 Ω
A23-1 (MTH+) - A21-7 (MTH+)	Power switch off	Below 1 Ω
A23-2 (MTH-) - A21-17 (MTH-)	Power switch off	Below 1 Ω
A23-7 (REQ+) - A21-6 (REQ+)	Power switch off	Below 1 Ω
A23-8 (REQ-) - A21-16 (REQ-)	Power switch off	Below 1 Ω
A23-9 (CLK+) - A21-5 (CLK+)	Power switch off	Below 1 Ω
A23-10 (CLK-) - A21-15 (CLK-)	Power switch off	Below 1 Ω

Standard Resistance (Check for Short)

Tester Connection	Switch Condition	Specified Condition
A23-5 (HTM+) or A21-8 (HTM+) - Body ground and other terminals	Power switch off	10 kΩ or higher
A23-4 (HTM-) or A21-18 (HTM-) - Body ground and other terminals	Power switch off	10 kΩ or higher
A23-1 (MTH+) or A21-7 (MTH+) - Body ground and other terminals	Power switch off	10 kΩ or higher
A23-2 (MTH-) or A21-17 (MTH-) - Body ground and other terminals	Power switch off	10 kΩ or higher
A23-7 (REQ+) or A21-6 (REQ+) - Body ground and other terminals	Power switch off	10 kΩ or higher
A23-8 (REQ-) or A21-16 (REQ-) - Body ground and other terminals	Power switch off	10 kΩ or higher
A23-9 (CLK+) or A21-5 (CLK+) - Body ground and other terminals	Power switch off	10 kΩ or higher
A23-10 (CLK-) or A21-15 (CLK-) - Body ground and other terminals	Power switch off	10 kΩ or higher

Connect the cable to the negative (-) auxiliary battery terminal.
Turn the power switch on (IG).

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

Standard Voltage

Tester Connection	Switch Condition	Specified Condition
A23-5 (HTM+) or A21-8 (HTM+) - Body ground	Power switch on (IG)	Below 1 V
A23-4 (HTM-) or A21-18 (HTM-) - Body ground	Power switch on (IG)	Below 1 V
A23-1 (MTH+) or A21-7 (MTH+) - Body ground	Power switch on (IG)	Below 1 V
A23-2 (MTH-) or A21-17 (MTH-) - Body ground	Power switch on (IG)	Below 1 V
A23-7 (REQ+) or A21-6 (REQ+) - Body ground	Power switch on (IG)	Below 1 V
A23-8 (REQ-) or A21-16 (REQ-) - Body ground	Power switch on (IG)	Below 1 V
A23-9 (CLK+) or A21-5 (CLK+) - Body ground	Power switch on (IG)	Below 1 V
A23-10 (CLK-) or A21-15 (CLK-) - Body ground	Power switch on (IG)	Below 1 V

NOTE:

Turning the power switch on (IG) with the inverter with converter assembly connector and the power management control ECU connector disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

Turn the power switch off.
Disconnect the cable from the negative (-) auxiliary battery terminal.
Reconnect the power management control ECU connector.
Reconnect the inverter with converter assembly connector.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to next step

INSPECT POWER MANAGEMENT CONTROL ECU

Disconnect the power management control ECU connector.

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

Fig 8: Measuring Resistance Of Power Management Control ECU Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Standard Resistance

Tester Connection	Switch Condition	Specified Condition
A23-5 (HTM+) - A23-4 (HTM-)	Power switch off	80 to 170 Ω
A23-1 (MTH+) - A23-2 (MTH-)	Power switch off	80 to 170 Ω
A23-7 (REQ+) - A23-8 (REQ-)	Power switch off	80 to 170 Ω
A23-9 (CLK+) - A23-10 (CLK-)	Power switch off	80 to 170 Ω

TEXT IN ILLUSTRATION

*a	Component with harness connected (Power Management Control ECU)

Reconnect the power management control ECU connector.

NG → See step 20

OK: Go to next step

CHECK CONNECTOR CONNECTION CONDITION (MOTOR RESOLVER CONNECTOR) See step 5
NG → CONNECT SECURELY

OK → See step 24
CHECK CONNECTOR CONNECTION CONDITION (MOTOR RESOLVER CONNECTOR) See step 6
NG → CONNECT SECURELY

OK: Go to next step
CHECK HARNESS AND CONNECTOR (INVERTER WITH CONVERTER ASSEMBLY - MOTOR RESOLVER) See step 7
NG → REPAIR OR REPLACE HARNESS OR CONNECTOR

OK → See step 21

CHECK HARNESS AND CONNECTOR (INVERTER WITH CONVERTER ASSEMBLY - PCU FUSE)

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 repair information because this may cause a malfunction.
Disconnect the inverter with converter assembly connector.

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

Fig 9: Measuring Resistance Of Inverter With Converter Assembly Connector

Standard Resistance

Tester Connection	Switch Condition	Specified Condition
A21-10 (+B) - Body ground	Power switch off	10 kΩ or higher
A21-9 (+B2) - Body ground	Power switch off	10 kΩ or higher

TEXT IN ILLUSTRATION

*a	Front view of wire harness connector (to Inverter with Converter Assembly)

Reconnect the inverter with converter assembly connector.

NG → See step 17

OK: Go to next step

REPLACE INVERTER WITH CONVERTER ASSEMBLY
Refer to COMPONENTS

NEXT → REPLACE FUSE (PCU)
REPAIR OR REPLACE HARNESS OR CONNECTOR
NEXT → REPLACE FUSE (PCU)

CHECK EV TRANSAXLE WITH MOTOR ASSEMBLY (MOTOR CABLE CONNECTION CONDITION)

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 repair information because this may cause a malfunction.
Check that the bolts for the motor cable are tightened to the specified torque, the motor cable is connected securely, and there are no contact problems.

Fig 10: Identifying Motor Cable Bolts
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Specified Condition

8.0 N*m (82 kgf*cm, 71 in.*lbf)

NOTE:
Make sure that the tightening torque of the bolts is between 6.4 and 9.6 N*m (65 and 98 kgf*cm, 57 and 85 in.*lbf).
Disconnect the motor cable from the EV transaxle with motor assembly.

Check for arc marks at the bolts and terminals for the motor cable.

Result

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

Connect the motor cable to the EV transaxle with motor assembly.

B → REPLACE MALFUNCTIONING PARTS

C → CONNECT SECURELY

A: Go to next step

CHECK MOTOR CABLE

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 repair information because this may cause a malfunction.
Remove the motor cable. Refer to COMPONENTS .

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

Fig 11: Measuring Resistance Of Motor Cable Connectors

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	Switch Condition	Specified Condition
U2-1 (W) - Body ground and shield ground	Power switch off	100 MΩ or higher
U2-2 (U) - Body ground and shield ground	Power switch off	100 MΩ or higher
U2-3 (V) - Body ground and shield ground	Power switch off	100 MΩ or higher

TEXT IN ILLUSTRATION

*1	Motor Cable (Inverter with Converter Assembly Side)
*2	Shield Ground
*3	Motor Cable (EV Transaxle with motor Assembly Side)

NOTE:

Wrap the terminal of the three-phase AC cable with insulating tape to prevent them from coming into contact with body ground.

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

Standard Resistance

Tester Connection	Switch Condition	Specified Condition
U2-1 (W) - U1-1 (W)	Power switch off	Below 1 Ω
U2-2 (U) - U1-3 (U)	Power switch off	Below 1 Ω
U2-3 (V) - U1-2 (V)	Power switch off	Below 1 Ω
U2-1 (W) - U1-3 (U)	Power switch off	100 MΩ or higher
U2-2 (U) - U1-2 (V)	Power switch off	100 MΩ or higher
U2-3 (V) - U1-1 (W)	Power switch off	100 MΩ or higher

Install the motor cable.

NG → See step 25

OK → See step 21

POWER MANAGEMENT CONTROL ECU MUST BE REPLACED
1. Even though it has been determined that the power management control ECU needs to be replaced, make sure to inspect the voltage difference between No. 1 EV battery and No. 2 EV battery before replacing it.
NEXT → See step 26
REPLACE EV TRANSAXLE WITH MOTOR ASSEMBLY. Refer to COMPONENTS
GO TO DTC CHART (HYBRID CONTROL SYSTEM). Refer to DIAGNOSTIC TROUBLE CODE CHART
GO TO DTC CHART (P0A78-202). Refer to DTC P0A78-202: Drive Motor "A" Inverter Performance
REPLACE INVERTER WITH CONVERTER ASSEMBLY. Refer to COMPONENTS
REPLACE MOTOR CABLE. Refer to COMPONENTS
GO TO NO. 1 EV BATTERY - NO. 2 EV BATTERY VOLTAGE DIFFERENCE INSPECTION. Refer to No. 1 EV Battery - No. 2 EV Battery Voltage Difference Inspection