Lexus ES: Hybrid/EV Battery Negative Contactor Actuator Stuck Closed (P0AA373)

Lexus ES (XZ10) Service Manual / Engine & Hybrid System / Hybrid / Battery Control / Hybrid Control System (for Lithium-ion Battery) / Hybrid/EV Battery Negative Contactor Actuator Stuck Closed (P0AA373)

DTC SUMMARY

MALFUNCTION DESCRIPTION

The hybrid vehicle control ECU detects a stuck closed malfunction of a system main relay on the HV battery negative side.

The cause of this malfunction may be one of the following:

Inverter voltage sensor (VH) internal circuit malfunction

Voltage sensor (VH) malfunction
Motor generator control ECU (MG ECU) malfunction
Communication (wire harness) malfunction

High voltage system malfunction

HV battery junction block assembly malfunction

Low-voltage circuit (12 V) malfunction

Hybrid vehicle control ECU malfunction
HV battery junction block assembly malfunction
Low voltage wire harness malfunction
Low voltage connector malfunction

DESCRIPTION

Refer to the description for DTC P0AE411.

Click here

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Warning Indicate
P0AA373	Hybrid/EV Battery Negative Contactor Actuator Stuck Closed	Even the system main relay of HV battery negative (-) terminal side is turned off, the inverter voltage (VH) does not drop. (1 trip detection logic)	HV battery junction block assembly Inverter with converter assembly Hybrid vehicle control ECU Wire harness or connector	Does not come on	Master Warning Light: Comes on

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Warning Indicate

P0AA373

Hybrid/EV Battery Negative Contactor Actuator Stuck Closed

Even the system main relay of HV battery negative (-) terminal side is turned off, the inverter voltage (VH) does not drop.

(1 trip detection logic)

HV battery junction block assembly
Inverter with converter assembly
Hybrid vehicle control ECU
Wire harness or connector

Does not come on

Master Warning Light:

Comes on

Related Data List

DTC No.	Data List
P0AA373	Hybrid/EV Battery Voltage VH-Voltage after Boosting VL-Voltage before Boosting

CONFIRMATION DRIVING PATTERN

HINT:

After repair has been completed, clear the DTC and then check that the vehicle has returned to normal by performing the following All Readiness check procedure.

Click here

Connect the Techstream to the DLC3.
Turn the power switch on (IG) and turn the Techstream on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the power switch off and wait for 2 minutes or more.
Turn the power switch on (IG) and turn the Techstream on.
Turn the power switch on (READY) and wait for 3 minutes or more.
HINT:

According to the display on the Techstream, read the Data List and monitor the values of "Hybrid/EV Battery Voltage" and "VL-Voltage before Boosting" for 3 minutes. If the difference between "Hybrid/EV Battery Voltage" and "VL-Voltage before Boosting" is always less than 100 V, the vehicle has returned to normal.
Enter the following menus: Powertrain / Hybrid Control / Utility / All Readiness.
Check the DTC judgment result.
HINT:
- If the judgment result shows NORMAL, the system is normal.
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows INCOMPLETE or N/A, perform driving pattern again.

WIRING DIAGRAM

Refer to the wiring diagram for the HV battery high-voltage line circuit.

Click here

CAUTION / NOTICE / HINT

CAUTION:

Before the following operations are conducted, take precautions to prevent electric shock by turning the power switch off, wearing insulated gloves, and removing the service plug grip from HV battery.
- Inspecting the high-voltage system
- Disconnecting the low voltage connector of the inverter with converter assembly
- Disconnecting the low voltage connector of the HV battery
To prevent electric shock, make sure to remove the service plug grip to cut off the high voltage circuit before servicing the vehicle.
After removing the service plug grip from the HV battery, put it in your pocket to prevent other technicians from accidentally reconnecting it while you are working on the high-voltage system.
After removing 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.
Click here

HINT:

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

*a

Without waiting for 10 minutes
Make sure to insulate the high-voltage connectors and terminals of the HV battery with insulating tape after removing it.
If the HV battery stored without insulating the connectors and terminals, electric shock or fire may result.

NOTICE:

After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work.
Click here
If the DTCs are cleared or the cable is disconnected and reconnected to the negative (-) auxiliary battery terminal before performing repairs, turning the power switch on (READY) may cause a malfunction. Do not turn the power switch on (READY).

HINT:

If DTC P0AA373 is output, the power switch cannot be turned on (READY).

PROCEDURE

1.	CHECK DTC OUTPUT (HYBRID CONTROL, MOTOR GENERATOR, HV BATTERY)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(d) Check for DTCs.

Powertrain > Hybrid Control > Trouble Codes Powertrain > Motor Generator > Trouble Codes Powertrain > HV Battery > Trouble Codes

Result	Proceed to
P0AA373 only is output, or DTCs except the ones in the table below are also output.	A
DTCs of hybrid control system in the tables below are output.	B
DTCs of motor generator control system in the tables below are output.	C
DTCs of hybrid battery system in the tables below are output.	D

Malfunction Content	System	Relevant DTC
Microcomputer malfunction	Hybrid control system	P060647	Hybrid/EV Powertrain Control Module Processor Watchdog / Safety MCU Failure
		P060687	Hybrid/EV Powertrain Control Module Processor to Monitoring Processor Missing Message
		P060A47	Hybrid/EV Powertrain Control Module Monitoring Processor Watchdog / Safety MCU Failure
		P060A87	Hybrid/EV Powertrain Control Module Processor from Monitoring Processor Missing Message
		P0A1B49	Drive Motor "A" Control Module Internal Electronic Failure
		P1C9E9F	Hybrid/EV System Reset Stuck Off
		P060B49	Hybrid/EV Powertrain Control Module A/D Processing Internal Electronic Failure
	Motor generator control system	P0A1B1F	Generator Control Module Circuit Intermittent
		P0A1A47	Generator Control Module Watchdog / Safety μC Failure
		P0A1A49	Generator Control Module Internal Electronic Failure
		P1C2A1C	Generator A/D Converter Circuit Circuit Voltage Out of Range
		P1C2A49	Generator A/D Converter Circuit Internal Electronic Failure
		P1C2B1C	Drive Motor "A" Control Module A/D Converter Circuit Voltage Out of Range
		P1C2B49	Drive Motor "A" Control Module A/D Converter Circuit Internal Electronic Failure
		P1CAC49	Generator Position Sensor Internal Electronic Failure
		P1CAD49	Drive Motor "A" Position Sensor Internal Electronic Failure
		P1CAF38	Generator Position Sensor REF Signal Cycle Malfunction Signal Frequency Incorrect
		P1CB038	Drive Motor "A" Position Sensor REF Signal Frequency Incorrect
		P313383	Communication Error from Generator to Drive Motor "A" Value of Signal Protection Calculation Incorrect
		P313386	Communication Error from Generator to Drive Motor "A" Signal Invalid
		P313387	Communication Error from Generator to Drive Motor "A" Missing Message
	Hybrid battery system	P060B49	Hybrid/EV Battery Energy Control Module A/D Processing Internal Electronic Failure
		P060687	Hybrid/EV Battery Energy Control Module Processor to Monitoring Processor Missing Message
		P060A47	Hybrid/EV Battery Energy Control Module Monitoring Processor Watchdog / Safety MCU Failure
		P060A87	Hybrid/EV Battery Energy Control Module Processor from Monitoring Processor Missing Message
		P060B16	Hybrid/EV Battery Energy Control Module A/D Processing Circuit Voltage Below Threshold
		P0E2D00	Hybrid/EV Battery Energy Control Module Hybrid/EV Battery Monitor Performance
Power source circuit malfunction	Motor generator control system	P06D61C	Generator Control Module Offset Power Circuit Voltage Out of Range
Power source circuit malfunction	Motor generator control system	P06B01C	Generator Control Module Position Sensor REF Power Source Circuit Voltage Out of Range
Communication system malfunction	Hybrid control system	P312387	Lost Communication with Drive Motor Control Module "A" from Hybrid/EV Control Module Missing Message
Communication system malfunction	Hybrid control system	U011187	Lost Communication with Hybrid/EV Battery Energy Control Module "A" Missing Message
Sensor and actuator circuit malfunction	Hybrid control system	P0AD911	Hybrid/EV Battery Positive Contactor Circuit Short to Ground
		P0AD915	Hybrid/EV Battery Positive Contactor Circuit Short to Auxiliary Battery or Open
		P0ADD11	Hybrid/EV Battery Negative Contactor Circuit Short to Ground
		P0ADD15	Hybrid/EV Battery Negative Contactor Circuit Short to Auxiliary Battery or Open
		P0AE411	Hybrid/EV Battery Precharge Contactor Circuit Short to Ground
		P0AE415	Hybrid/EV Battery Precharge Contactor Circuit Short to Auxiliary Battery or Open
	Motor generator control system	P0A3F16	Drive Motor "A" Position Sensor Circuit Voltage Below Threshold
		P0A4B16	Generator Position Sensor Circuit Voltage Below Threshold
		P0A4B21	Generator Position Sensor Signal Amplitude < Minimum
		P0A4B22	Generator Position Sensor Signal Amplitude > Maximum
		P0C5013	Drive Motor "A" Position Sensor Circuit "A" Circuit Open
		P0C5016	Drive Motor "A" Position Sensor Circuit "A" Circuit Voltage Below Threshold
		P0C5017	Drive Motor "A" Position Sensor Circuit "A" Circuit Voltage Above Threshold
		P0C5A13	Drive Motor "A" Position Sensor Circuit "B" Circuit Open
		P0C5A16	Drive Motor "A" Position Sensor Circuit "B" Circuit Voltage Below Threshold
		P0C5A17	Drive Motor "A" Position Sensor Circuit "B" Circuit Voltage Above Threshold
		P0C6413	Generator Position Sensor Circuit "A" Circuit Open
		P0C6416	Generator Position Sensor Circuit "A" Circuit Voltage Below Threshold
		P0C6417	Generator Position Sensor Circuit "A" Circuit Voltage Above Threshold
		P0C6913	Generator Position Sensor Circuit "B" Circuit Open
		P0C6916	Generator Position Sensor Circuit "B" Circuit Voltage Below Threshold
		P0C6917	Generator Position Sensor Circuit "B" Circuit Voltage Above Threshold
	Hybrid battery system	P301A1C	Hybrid Battery Stack 1 Cell Voltage Detection Voltage Out of Range
		P1A001C	Hybrid Battery Stack 2 Cell Voltage Detection Voltage Out of Range
		P1AFD1C	Flying Capacitor/Internal Control Module Hybrid/EV Battery Monitor Voltage Out of Range
System malfunction	Hybrid control system	P0C7600	Hybrid/EV Battery System Discharge Time Too Long
		P0D2D1C	Drive Motor "A" Inverter Voltage Sensor Voltage Out of Range
		P1C8349	High Voltage Power Resource Circuit Voltage Sensor after Boosting Malfunction
	Motor generator control system	P0D2D16	Drive Motor "A" Inverter Voltage Sensor (VH) Circuit Voltage Below Threshold
		P0D2D17	Drive Motor "A" Inverter Voltage Sensor (VH) Circuit Voltage Above Threshold
		P1CB69E	Drive Motor "A" Inverter Voltage Sensor (VH) Stuck On

HINT:

P0AA373 may be output as a result of the malfunction indicated by the DTCs above.
1. The chart above is listed in inspection order of priority.
2. Check DTCs that are output at the same time by following the listed order. (The main cause of the malfunction can be determined without performing unnecessary inspections.)

(e) Turn the power switch off.

GO TO DTC CHART (HYBRID CONTROL SYSTEM)

GO TO DTC CHART (MOTOR GENERATOR CONTROL SYSTEM)

GO TO DTC CHART (HYBRID BATTERY SYSTEM)

2.	CHECK FREEZE FRAME DATA (HYBRID CONTROL)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(d) Read the freeze frame data of DTC P0AA373.

Powertrain > Hybrid Control > Trouble Codes

NOTICE:

As freeze frame data is stored immediately before and after a DTC is stored, make sure to only read the values for the moment the DTC was stored ("0(s)").

Result	Proceed to
Difference between "VL-Voltage before Boosting" and "VH-Voltage after Boosting" is less than 76 V.	A
Difference between "VL-Voltage before Boosting" and "VH-Voltage after Boosting" is 76 V or more.	B

HINT:

If VH-Voltage after Boosting is output even when an off command is being sent to the system main relay (positive side), P0AA373 is output. If the difference between the "VL-Voltage before Boosting" and the "VH-Voltage after Boosting" is large, it is determined that there is an inverter (VH sensor) malfunction.

(e) Turn the power switch off.

REPLACE INVERTER WITH CONVERTER ASSEMBLY

3.	CHECK CONNECTOR CONNECTION CONDITION (HYBRID VEHICLE CONTROL ECU CONNECTOR)

Click here

GO TO STEP 5

4.	CONNECT SECURELY

5.	CHECK CONNECTOR CONNECTION CONDITION (FLOOR WIRE CONNECTOR)

Click here

Result	Proceed to
OK	A
NG (The connector is not connected securely.)	B
NG (The terminals are not making secure contact or are deformed, or water or foreign matter exists in the connector.)	C

GO TO STEP 8

GO TO STEP 7

6.	CONNECT SECURELY

GO TO STEP 8

7.	REPAIR OR REPLACE HARNESS OR CONNECTOR

8.	CHECK CONNECTOR CONNECTION CONDITION (HV BATTERY JUNCTION BLOCK ASSEMBLY CONNECTOR)

Click here

GO TO STEP 10

9.	CONNECT SECURELY

10.	CHECK GROUND WIRE CONNECTION CONDITION (SMR ACTIVATION LOW-VOLTAGE CIRCUIT)

Click here

GO TO STEP 12

11.	CONNECT SECURELY

12.	CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - HV BATTERY JUNCTION BLOCK ASSEMBLY)

CAUTION:

Be sure to wear insulated gloves.

(a) Check that the service plug grip is not installed.

NOTICE:

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.

(b) Remove the No. 1 HV battery cover panel RH.

Click here

(d) Disconnect the G59 hybrid vehicle control ECU connector.

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

Standard Resistance (Check for Open):

Tester Connection	Condition	Specified Condition
G59-1 (SMRG) - N22-4 (SMRG)	Power switch off	Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection	Condition	Specified Condition
G59-1 (SMRG) or N22-4 (SMRG) - Body ground and other terminals	Power switch off	10 kΩ or higher

Rear view of wire harness connector

(to Hybrid Vehicle Control ECU)

Front view of wire harness connector

(to HV Battery Junction Block Assembly)

(f) Reconnect the G59 hybrid vehicle control ECU connector.

(g) Reconnect the N22 HV battery junction block assembly connector.

(h) Install the No. 1 HV battery cover panel RH.

GO TO STEP 14

13.	REPAIR OR REPLACE HARNESS OR CONNECTOR

14.	CHECK HARNESS AND CONNECTOR (HV BATTERY JUNCTION BLOCK ASSEMBLY - BODY GROUND)

Click here

GO TO STEP 16

15.	REPAIR OR REPLACE HARNESS OR CONNECTOR

16.	INSPECT HV BATTERY JUNCTION BLOCK ASSEMBLY (SMRG)

CAUTION:

Be sure to wear insulated gloves.

(a) Check that the service plug grip is not installed.

NOTICE:

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.

(b) Remove the No. 1 HV battery cover panel RH.

Click here

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

Component without harness connected

(HV Battery Junction Block Assembly)

Standard Resistance:

Tester Connection	Condition	Specified Condition
N22-4 (SMRG) - N22-3 (GND)	-40 to 80°C (-40 to 176°F)	19.0 to 59.0 Ω

(e) Reconnect the N22 HV battery junction block assembly connector.

(f) Install the No. 1 HV battery cover panel RH.

GO TO STEP 19

17.	CHECK HV BATTERY JUNCTION BLOCK ASSEMBLY (SMRG)

CAUTION:

Be sure to wear insulated gloves.

(a) Check that the service plug grip is not installed.

NOTICE:

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.

(b) Remove the No. 1 HV battery cover panel RH.

Click here

(d) Disconnect the HV battery high voltage connector and electric vehicle battery plug connector from the HV battery junction block assembly.

NOTICE:

Insulate each disconnected high-voltage connector with insulating tape. Wrap the connector from the wire harness side to the end of the connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
a3-1 (CEI) - y12-1 (-)	Power switch off	10 kΩ or higher

HINT:

If a system main relay is stuck closed, inspect the HV battery junction block assembly without removing it from the vehicle, in order to keep the relay closed.
If the result of reading the freeze frame data is A, the HV battery junction block assembly must be replaced. Measuring resistance can determine that this is either a present or past malfunction.

*a	Component without harness connected (HV Battery Junction Block Assembly)

(f) Reconnect the HV battery high voltage connector and electric vehicle battery plug connector.

(g) Reconnect the 2 HV floor under wire connectors.

(h) Install the No. 1 HV battery cover panel RH.

Result	Judgment	Proceed to
OK	Past malfunction	A
NG	Present malfunction	B

GO TO STEP 20

18.	REPLACE HV BATTERY JUNCTION BLOCK ASSEMBLY

Click here

GO TO STEP 21

19.	REPLACE HV BATTERY JUNCTION BLOCK ASSEMBLY

Click here

GO TO STEP 21

20.	REPLACE HV BATTERY JUNCTION BLOCK ASSEMBLY

Click here

21.	CHECK HYBRID VEHICLE CONTROL ECU (CHECK FOR NORMAL OPERATION)

Click here

Result	Proceed to
Difference between "Hybrid/EV Battery Voltage" and "VL-Voltage before Boosting" is always less than 100 V.	A
Difference between "Hybrid/EV Battery Voltage" and "VL-Voltage before Boosting" is 100 V or more.	B

END

REPLACE HYBRID VEHICLE CONTROL ECU AND HV BATTERY JUNCTION BLOCK ASSEMBLY

SEE MORE:

Data List / Active Test

DATA LIST / ACTIVE TEST READ DATA LIST HINT: Using the Techstream to read the Data List allows the values or states of switches, sensors, actuators and other items to be read without removing any parts. This non-intrusive inspection can be very useful because intermittent conditions or signals may b

Components

COMPONENTS ILLUSTRATION *1 BATTERY CLAMP SUB-ASSEMBLY - - N*m (kgf*cm, ft.*lbf): Specified torque - - ILLUSTRATION *1 FRONT LOWER NO. 1 FLOOR HEAT INSULATOR - - N*m (kgf*cm, ft.*lbf): Specified torque - - ILLUSTRATION *1 NO. 1 CONSOLE BOX DUCT

Lexus ES: Hybrid/EV Battery Negative Contactor Actuator Stuck Closed (P0AA373)

READ NEXT:

Hybrid/EV Battery Voltage System Isolation Internal Electronic Failure (P0AA649,P1C7C49-P1C7F49)

Hybrid/EV Battery Voltage Isolation Sensor Circuit Internal Electronic Failure (P0AA749)

Hybrid/EV Battery Current Sensor "A" Circuit Range/Performance (P0ABF00)

SEE MORE:

Data List / Active Test

Components