HYBRID CONTROL SYSTEM, Diagnostic DTC:P0A78-120

DTC Code	DTC Name
P0A78-120	Drive Motor "A" Inverter Performance

DESCRIPTION

For a description of the inverter, Click here.

If an overvoltage occurs in the motor inverter, generator inverter or rear motor inverter, the MG ECU detects it and transmits this information to the power management control ECU (HV CPU).

DTC No.	INF Code	DTC Detection Condition	Trouble Area
P0A78	120	Motor inverter overvoltage signal detection (overvoltage (rear transaxle malfunction))	Inverter with converter assembly Rear traction motor with transaxle assembly Wire harness or connector

WIRING DIAGRAM

Refer to the wiring diagram for DTC P0A1A-200 Click here.

INSPECTION PROCEDURE

CAUTION:

Before inspecting the high-voltage system or disconnecting the low voltage connector of the inverter with converter assembly, take safety precautions such as wearing insulated gloves and removing the service plug grip to prevent electrical shocks. After removing the service plug grip, put it in your pocket to prevent other technicians from accidentally reconnecting it while you are working on the high-voltage system.
After disconnecting the service plug grip, wait for at least 10 minutes before touching any of the high-voltage connectors or terminals. After waiting for 10 minutes, check the voltage at the terminals in the inspection point in the inverter with converter assembly. The voltage should be 0 V before beginning work.

Tech Tips

Waiting for at least 10 minutes is required to discharge the high-voltage capacitor inside the inverter with converter assembly.

PROCEDURE

CHECK DTC OUTPUT (HV)

Connect the intelligent tester to the DLC3.
Turn the power switch on (IG).
Enter the following menus: Powertrain / Hybrid Control / Trouble Codes.

Check if DTCs are output.

Result

Result	Proceed to
P0A78-120 only is output	A
Any of the following DTCs are also output	B

DTC No.	Relevant Diagnosis
P0A1A (all INF codes)*1	Generator Control Module
P0A1B (all INF codes)*1	Drive Motor "A" Control Module
P0A1C (all INF codes)*1	Drive Motor "B" Control Module
P0A1D (all INF codes)*1	Hybrid Powertrain Control Module
P0A60 (all INF codes)*1	Drive Motor "A" Phase V Current
P0A63 (all INF codes)*1	Drive Motor "A" Phase W Current
P0A69 (all INF codes)*1	Drive Motor "B" Phase V Current
P0A6C (all INF codes)*1	Drive Motor "B" Phase W Current
P0A72 (all INF codes)*1	Generator Phase V Current
P0A75 (all INF codes)*1	Generator Phase W Current
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
P0A45-669	Drive Motor "B" Position Sensor Circuit
P0A46-671	Drive Motor "B" Position Sensor Circuit Range/Performance
P0A47-670	Drive Motor "B" Position Sensor Circuit Low
P0A4B-253	Generator Position Sensor Circuit
P0A4C-513	Generator Position Sensor Circuit Range/Performance
P0A4D-255	Generator Position Sensor Circuit Low
P0A78-266, 267, 287, 505, 506, 586, 806, 807, 808	Drive Motor "A" Inverter Performance
P0A79-693, 694, 695, 812, 813, 814	Drive Motor "B" Inverter Performance
P0A7A-325, 517, 518, 809, 810, 811	Generator Inverter Performance
P0A94-169, 170, 171, 554, 555, 556, 585, 587, 589, 590	DC/DC Converter Performance
P0ADB-227	Hybrid Battery Positive Contactor Control Circuit Low
P0ADC-226	Hybrid Battery Positive Contactor Control Circuit High
P0ADF-229	Hybrid Battery Negative Contactor Control Circuit Low
P0AE0-228	Hybrid Battery Negative Contactor Control Circuit High
P0C76-523	Hybrid Battery System Discharge Time Too Long
P3004-803	High Voltage Power Resource

Tech Tips

*1: If any INF codes are output for this DTC, refer to the corresponding diagnostic procedure.
P0A78-120 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.

GO TO DTC CHART Click here

CHECK CONNECTOR CONNECTION CONDITION (INVERTER WITH CONVERTER ASSEMBLY CONNECTOR)
CAUTION:

Be sure to wear insulated gloves.
1. 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 manual because this may cause a malfunction.
  
  Note
  
  Before disconnecting the connector, confirm that it is properly connected by checking that the locking claws are engaged and that the connector does not pull out.
2. Check the connection of the low voltage connector of the inverter with converter assembly.
  
  OK
  
  The connector is connected securely and there are no contact problems.
  
  Tech Tips
  
  When connecting the connector, insert it with the locking lever in the raised position. Rotate the lever downward and make sure that the connector is pulled into its socket. When the locking lever is in its fully closed position, a click will be heard as its locking claws engage. After the click is heard, pull up on the connector to confirm that it is properly connected.
NG
CONNECT SECURELY

OK

OK
The connector is connected securely and there are no contact problems.

CHECK HARNESS AND CONNECTOR (INVERTER WITH CONVERTER ASSEMBLY - REAR MOTOR RESOLVER)

CAUTION:

Be sure to wear insulated gloves.

Disconnect the low voltage connector A79 from the inverter with converter assembly.
Turn the power switch on (IG).

Text in Illustration
*1	Front view of wire harness connector (to Inverter with Converter Assembly)

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

Standard Voltage

Tester Connection	Switch Condition	Specified Condition
A79-34 (RRF) - Body ground	Power switch on (IG)	Below 1 V
A79-23 (RRFG) - Body ground	Power switch on (IG)	Below 1 V
A79-33 (RSN) - Body ground	Power switch on (IG)	Below 1 V
A79-22 (RSNG) - Body ground	Power switch on (IG)	Below 1 V
A79-32 (RCS) - Body ground	Power switch on (IG)	Below 1 V
A79-21 (RCSG) - Body ground	Power switch on (IG)	Below 1 V

Note

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

Turn the power switch off.
Connect the inverter with converter assembly connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR

CHECK REAR MOTOR RESOLVER

Disconnect the low voltage connector A79 from the inverter with converter assembly.

Text in Illustration
*1	Front view of wire harness connector (to Inverter with Converter Assembly)

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

Standard Resistance (Check for Open)

Tester Connection	Switch Condition	Specified Condition
A79-34 (RRF) - A79-23 (RRFG)	Power switch off	4.2 to 12.5 Ω
A79-33 (RSN) - A79-22 (RSNG)	Power switch off	9.8 to 20.1 Ω
A79-32 (RCS) - A79-21 (RCSG)	Power switch off	9.8 to 20.1 Ω

Standard Resistance (Check for Short)

Tester Connection	Switch Condition	Specified Condition
A79-34 (RRF) or A79-23 (RRFG) - Body ground and other terminals	Power switch off	10 kΩ or higher
A79-33 (RSN) or A79-22 (RSNG) - Body ground and other terminals	Power switch off	10 kΩ or higher
A79-32 (RCS) or A79-21 (RCSG) - Body ground and other terminals	Power switch off	10 kΩ or higher

Connect the inverter with converter assembly connector.

Click here

CHECK CONNECTOR CONNECTION CONDITION (REAR MOTOR RESOLVER CONNECTOR)
1. Check the connection of the rear motor resolver connector.
  
  OK
  
  The connector is connected securely and there are no contact problems.
NG
CONNECT SECURELY

OK

REPLACE INVERTER WITH CONVERTER ASSEMBLY Click here
CHECK CONNECTOR CONNECTION CONDITION (REAR MOTOR RESOLVER CONNECTOR)
1. Check the connection of the rear motor resolver connector.
  
  OK
  
  The connector is connected securely and there are no contact problems.
NG
CONNECT SECURELY

OK

OK
The connector is connected securely and there are no contact problems.

OK
The connector is connected securely and there are no contact problems.

CHECK HARNESS AND CONNECTOR (INVERTER WITH CONVERTER ASSEMBLY - REAR MOTOR RESOLVER)

Disconnect the low voltage connector A79 from the inverter with converter assembly.

Text in Illustration
*1	Front view of wire harness connector (to Rear Motor Resolver)
*2	Front view of wire harness connector (to Inverter with Converter Assembly)

Disconnect the rear motor resolver connector.

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

Standard Resistance (Check for Open)

Tester Connection	Switch Condition	Specified Condition
g11-1 (RRF) - A79-34 (RRF)	Power switch off	Below 1 Ω
g11-4 (RRFG) - A79-23 (RRFG)	Power switch off	Below 1 Ω
g11-2 (RSN) - A79-33 (RSN)	Power switch off	Below 1 Ω
g11-5 (RSNG) - A79-22 (RSNG)	Power switch off	Below 1 Ω
g11-3 (RCS) - A79-32 (RCS)	Power switch off	Below 1 Ω
g11-6 (RCSG) - A79-21 (RCSG)	Power switch off	Below 1 Ω

Standard Resistance (Check for Short)

Tester Connection	Switch Condition	Specified Condition
g11-1 (RRF) or A79-34 (RRF) - Body ground and other terminals	Power switch off	10 kΩ or higher
g11-4 (RRFG) or A79-23 (RRFG) - Body ground and other terminals	Power switch off	10 kΩ or higher
g110-2 (RSN) or A79-33 (RSN) - Body ground and other terminals	Power switch off	10 kΩ or higher
g11-5 (RSNG) or A79-22 (RSNG) - Body ground and other terminals	Power switch off	10 kΩ or higher
g11-3 (RCS) or A79-32 (RCS) - Body ground and other terminals	Power switch off	10 kΩ or higher
g11-6 (RCSG) or A79-21 (RCSG) - Body ground and other terminals	Power switch off	10 kΩ or higher

Tech Tips

The rear motor resolver is not available separately. If it requires replacement, replace the rear traction motor with transaxle assembly.

Connect the rear motor resolver connector.
Connect the inverter with converter assembly connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE REAR TRACTION MOTOR WITH TRANSAXLE ASSEMBLY Click here