Nissan Altima HL32 Hybrid. Manual - part 634

P0A78-510

HBC-285

< COMPONENT DIAGNOSIS >

D

E

F

G

H

I

J

K

L

M

A

B

HBC

N

O

P

The MG ECU monitors the inverter voltage and detects malfunctions.

DTC Logic

INFOID:0000000004211943

DTC DETECTION LOGIC

Upon receiving a motor gate shutdown signal from the MG ECU, the inverter forcibly stops MG2 by turning off

all power transistors that are actuating MG2.

The MG ECU monitors the motor gate shutdown signal line and detects malfunctions.

The MG ECU monitors the current that flows in MG2. If the current flows in MG2 while the vehicle is stationary

with the ignition switch ON or the shift lever in the N position, the MG ECU will detect a malfunction. The hybrid

vehicle control ECU will illuminate the MIL and set a DTC.

JMCIA0099GB

HBC-286

< COMPONENT DIAGNOSIS >

P0A78-510

NOTE:

• If DTC P0A78-510 is output, the hybrid system cannot be restarted until the DTC is cleared.

• If the malfunction is not reproduced, leave the vehicle for 1 minute with the shift lever in the N position in

order to easily reproduce the malfunction.

Diagnosis Procedure

INFOID:0000000004211944

1.

PRECONDITIONING

• 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.

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

converter assembly.

>> GO TO 2.

2.

CHECK CONNECTOR CONNECTION CONDITION (INVERTER WITH CONVERTER ASSEMBLY CON-

NECTOR)
See 

HBC-109, "Diagnosis Procedure"

.

OK or NG

OK

>> Replace inverter with converter assembly (See 

HBC-638, "Removal and Installation"

).

NG

>> Connect securely.

DTC No.

INF code

Trouble diagnosis name

DTC detecting condition

Possible cause

P0A78

510

Drive Motor “A” Inverter 
Performance

Motor inverter gate malfunction

Inverter with converter assembly

P0A78-523

HBC-287

< COMPONENT DIAGNOSIS >

D

E

F

G

H

I

J

K

L

M

A

B

HBC

N

O

P

P0A78-523

Description

INFOID:0000000004211945

The inverter converts high-voltage direct current from the HV battery and alternating current for MG2 and

MG1. The inverter contains a three-phase bridge circuit, which consists of six power transistors each for MG2

and MG1, that converts direct current to three-phase alternating current. The MG ECU controls the actuation

of the power transistors. The inverter transmits information that is necessary for effecting control, such as the

amperage and voltage, to the MG ECU.

The MG ECU uses a voltage sensor, which is built into the inverter, to detect boosted high voltage to allow

control of the voltage boost.

The inverter voltage sensor outputs voltage that varies between 0 and 5 V in accordance with the changes in

the high voltage. The higher the high voltage, the higher the output voltage, and the lower the high voltage, the

lower the output voltage.

HBC-288

< COMPONENT DIAGNOSIS >

P0A78-523

The MG ECU monitors the inverter voltage and detects malfunctions.

DTC Logic

INFOID:0000000004211946

DTC DETECTION LOGIC

The hybrid vehicle control ECU monitors the inverter voltage (VH) sensor signal. If the hybrid vehicle control

ECU detects a fault in the sensor signal, the hybrid vehicle control ECU interprets this as a VH sensor mal-

function. The hybrid vehicle control ECU will illuminate the MIL and set a DTC.

NOTE:

JMCIA0099GB

DTC No.

INF Code

Trouble diagnosis name

DTC detecting condition

Possible cause

P0A78

523

Drive Motor “A” Inverter Performance

Inverter voltage (VH) sensor 
offset malfunction

Inverter with converter assembly