Toyota Avalon (XX50): High Voltage Power Resource Circuit Short during Ready ON (P1C8449)

DTC SUMMARY

MALFUNCTION DESCRIPTION

The hybrid vehicle control ECU monitors the high-voltage wiring between the HV battery and inverter with converter assembly and detects an open circuit malfunction.

HINT:

• This DTC is differentiated from P300449 based on detection timing (after power switch is turned on (READY)). If P300449 is also output at the same time, first perform troubleshooting for P300449.
• If there is a SMRG stuck open malfunction, only P1C8449 is output.

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

Inverter voltage sensor (VH or VL) internal circuit malfunction

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

High voltage system malfunction

• HV battery malfunction
• HV battery junction block assembly malfunction
• Inverter with converter assembly malfunction
• High-voltage wire harness malfunction
• High-voltage connector or connection 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.

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DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Warning Indicate
P1C8449	High Voltage Power Resource Circuit Short during Ready ON	High-voltage circuit malfunctions between the HV battery and inverter with converter assembly. The voltage before boosting continues to be out of the HV battery voltage range or the integrated value of variation amount of the voltage before boosting for a specified period of time is large while the power switch is on (READY). The EV electric battery fuse is blown, the service plug grip is removed, SMRB or SMRG remains open, or the high-voltage cable has an open circuit. (1 trip detection logic)	HV battery junction block assembly Wire harness or connector Hybrid vehicle control ECU	Comes on	Master Warning Light: Comes on

Related Data List

DTC No.	Data List
P1C8449	Hybrid Battery Voltage Hybrid Battery Current VL-Voltage before Boosting VH-Voltage after Boosting

The following items can be helpful when performing repairs:

Data List

• Ready Signal

MONITOR DESCRIPTION

A malfunction is detected and the MIL is illuminated when the following condition is met:

A large fluctuation of DC/DC converter voltage is occurred due to power cable disconnection.

MONITOR STRATEGY

Related DTCs	P3004 (INF P1C8449): Power Cable Malfunction
Required sensors/components	DC/DC converter, HV battery
Frequency of operation	-
Duration	TMC's intellectual property
MIL operation	1 driving cycle
Sequence of operation	None

TYPICAL ENABLING CONDITIONS

The monitor will run whenever the following DTCs are not stored	TMC's intellectual property
Other conditions belong to TMC's intellectual property	-

TYPICAL MALFUNCTION THRESHOLDS

TMC's intellectual property

-

COMPONENT OPERATING RANGE

Hybrid vehicle control ECU

P3004 (INF P1C8449) is not detected

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

• When clearing the permanent DTCs, refer to the "CLEAR PERMANENT DTC" procedure.

  Click here

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG) and turn the Techstream on.
3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
4. Turn the power switch off and wait for 2 minutes or more.
5. Turn the power switch on (IG) and turn the Techstream on.
6. Turn the power switch on (READY) and wait for 3 minutes or more. [*1]

   HINT:

   • According to the display on the Techstream, read the Data List and monitor the values of "Hybrid Battery Voltage" and "VL-Voltage before Boosting" for 3 minutes. If the difference between "Hybrid Battery Voltage" and "VL-Voltage before Boosting" is always less than 50 V, the vehicle has returned to normal.
   • [*1] : Normal judgment procedure.

     The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.

7. Enter the following menus: Powertrain / Hybrid Control / Utility / All Readiness.
8. 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 the normal judgment procedure again.

WIRING DIAGRAM

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

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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

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.

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PROCEDURE

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

(a) Connect the Techstream to the DLC3.

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

(c) Enter the following menus: Powertrain / Hybrid Control and Motor Generator / Trouble Codes.

(d) Check for DTCs.

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

Result	Proceed to
P1C8449 only is output, or P0A9563 and 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
P0A9563 is also output.	D

Malfunction Content	System	Relevant DTC
Microcomputer malfunction	Hybrid control system	P0A1B49	Drive Motor "A" Control Module Internal Electronic Failure
		P060647	Hybrid/EV Powertrain Control Module Processor Watchdog / Safety MCU 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
		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
Power source circuit malfunction	Motor generator control system	P06D61C	Generator Control Module Offset Power 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
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
		P0E311C	Boosting Converter Voltage Sensor "A" Voltage Out of Range
	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
		P0CA300	DC/DC Converter Step Up Voltage Performance

HINT:

• P1C8449 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.

B

GO TO DTC CHART (HYBRID CONTROL SYSTEM)

C

GO TO DTC CHART (MOTOR GENERATOR CONTROL SYSTEM)

D

GO TO DTC CHART (P0A9563)

A

2.

CLEAR DTC

Click here

NEXT

3.	CHECK DTC OUTPUT (HYBRID CONTROL)

(a) Connect the Techstream to the DLC3.

(b) With the vehicle stopped, apply the parking brake and turn the power switch on (READY).

HINT:

• If the power switch could not be turned on (READY), turn the power switch off and check for DTCs after turning the power switch on (READY) again.
• Because P300449 uses 2 trip detection logic, the DTC detection conditions need to be met 2 times.

(c) Ensure the safety of the areas in front and at the back of the vehicle.

(d) Move the shift lever to D and depress both the accelerator pedal and brake pedal at the same time.

HINT:

Depressing both the accelerator pedal and brake pedal at the same time causes the HV battery current to flow and ensures that there is no problem with the high-voltage wiring.

(e) Enter the following menus: Powertrain / Hybrid Control / Trouble Codes.

(f) Check for DTCs.

Powertrain > Hybrid Control > Trouble Codes

Result	Proceed to
P1C8449 is output, or no DTCs are output.	A
Power switch could not be turned on (READY) and DTC P300449 is output.	B

(g) Turn the power switch off.

B

GO TO DTC CHART (P300449)

A

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

Click here

NG

CONNECT SECURELY

OK

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

B

CONNECT SECURELY

C

REPAIR OR REPLACE HARNESS OR CONNECTOR

A

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

Click here

NG

CONNECT SECURELY

OK

7.	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

(c) Disconnect the K18 HV battery junction block assembly connector.

(d) Disconnect the G46 hybrid vehicle control ECU connector.

(e) Measure the resistance according to the value(s) in the table below. Standard Resistance: Tester Connection Condition Specified Condition G46-4 (SMRB) - K18-1 (SMRB) Power switch off Below 1 Ω G46-1 (SMRG) - K18-4 (SMRG) Power switch off Below 1 Ω

*a Rear view of wire harness connector (to Hybrid Vehicle Control ECU) *b Front view of wire harness connector (to HV Battery Junction Block Assembly)

(f) Reconnect the G46 hybrid vehicle control ECU connector.

(g) Reconnect the K18 HV battery junction block assembly connector.

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

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

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

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

(c) Disconnect the K18 HV battery junction block assembly connector.

(d) Measure the resistance according to the value(s) in the table below. Standard Resistance: Tester Connection Condition Specified Condition K18-3 (GND) - Body ground Power switch off Below 1 Ω

*a Front view of wire harness connector (to HV Battery Junction Block Assembly)

(e) Reconnect the K18 HV battery junction block assembly connector.

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

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

9.	REPLACE HV BATTERY JUNCTION BLOCK ASSEMBLY

Click here

NEXT

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

CAUTION:

Be sure to wear insulated gloves.

(a) Install the service plug grip.

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

(c) Clear the DTCs.

Click here

(d) Turn the power switch off and wait for 2 minutes or more.

(e) Turn the power switch on (READY).

(f) Enter the following menus: Powertrain / Hybrid Control / Data List / Hybrid Battery Voltage, VL-Voltage before Boosting.

(g) According to the display on the Techstream, read the Data List and monitor the values of "Hybrid Battery Voltage" and "VL-Voltage before Boosting" for 3 minutes.

Powertrain > Hybrid Control > Data List

Tester Display
VL-Voltage before Boosting
Hybrid Battery Voltage

Result	Proceed to
Difference between "Hybrid Battery Voltage" and "VL-Voltage before Boosting" is always less than 50 V.	A
Difference between "Hybrid Battery Voltage" and "VL-Voltage before Boosting" is 50 V or more.	B

(h) Turn the power switch off.

A

END

B

REPLACE HYBRID VEHICLE CONTROL ECU