Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Hybrid/EV Battery Cell Low Voltage (P1AC000)

DESCRIPTION

The hybrid vehicle control ECU controls the SOC (state of charge) of the HV battery at a constant level during driving. The HV battery is composed of 34 modules, and each module consists of six 1.2 V cells in series. The battery voltage sensor monitors battery block voltage at 11 locations.

HINT:

• *1: Under normal conditions, the values of Hybrid Battery Block 1, 2, 9, 10 and 11 Voltage will be approximately 16 V and Hybrid Battery Block 3, 4, 5, 6, 7 and 8 Voltage will be approximately 32 V.
• If there is a short or open in a battery block voltage detection line, the value of Hybrid Battery Block Voltage for the corresponding battery block will be lower than 8 V.

The following items can be helpful when performing repairs:

• Internal Resistance 1 to 11
• Ready Signal
• Vehicle Speed
• Accelerator Position
• Shift Position
• Engine Speed
• Hybrid Battery Voltage
• Hybrid Battery Current
• BATT Voltage
• Hybrid Battery SOC just after IG-ON
• Hybrid Battery Maximum SOC
• Hybrid Battery Minimum SOC
• Total Distance Traveled
• Distance from DTC Cleared
• Engine Run Time

• Hybrid Battery Voltage Low

HINT:

• This DTC can be stored after clearing DTCs and driving the vehicle for approximately 10 minutes. (As 2 trip detection logic is used, check for DTCs including pending DTCs.)
• DTC P1AC000 is stored when a malfunction is detected in the HV battery or battery voltage sensor. If the HV battery is malfunctioning, the malfunction may not be reproduced when the condition of the HV battery changes due to a difference in driving load (amperage), battery SOC and battery temperature. Therefore, use the freeze frame data when performing a repair.
  1. When the HV battery is malfunctioning:
     • - Voltage of 1 or few battery blocks has dropped. The difference of voltage value between the hybrid battery block 1 and 2, 3 and 4, 4 and 5, 5 and 6, 6 and 7, 7 and 8, 9 and 10 or 10 and 11 is 1.2 V or more.
     • - Voltage of all battery blocks is output randomly with no certain pattern.
  2. When the battery voltage sensor is malfunctioning:
     • - Differences in battery block voltages have a certain pattern.
• In order to ensure HV battery performance, appropriate cooling performance must be maintained. Perform the following items as necessary. If cooling performance has decreased and "Maintenance Required for Traction Battery Cooling Parts See Owner's Manual" is displayed on the multi-information display, make sure to perform the following items:
  • Make sure the air intake port is not blocked.
  • Make sure there are no gaps between the connecting parts of the ducts.
  • Clean the No. 1 HV battery intake filter.
    • Clear the DTCs to reset the learning values even if no DTCs are stored.

MONITOR DESCRIPTION

The battery voltage sensor, which monitors the voltage of the battery blocks, determines that a malfunction has occurred if a voltage difference between the battery blocks exceeds the standard. When the malfunction detection condition is satisfied, the hybrid vehicle control ECU will illuminate the MIL and store a DTC.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

COMPONENT OPERATING RANGE

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.

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

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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. Drive the vehicle on urban roads for approximately 10 minutes.[*1]

   HINT:

   • This DTC may not be stored if the vehicle is stopped or being driven at a constant speed.
   • [*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.

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.

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  *a	Without waiting for 10 minutes

  HINT:

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

• 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.

• When disposing of an HV battery, make sure to return it through an authorized collection agent who is capable of handling it safely. If the HV battery is returned via the manufacturer specified route, it will be returned properly and in a safe manner by an authorized collection agent.

  *a	Dealer
  *b	Battery Collection Agent

  • Accidents such as electric shock may result if the HV battery is disposed of improperly or abandoned. Therefore, make sure to return all HV batteries through an authorized collection agent.
• After removing the HV battery, keep it away from water. Exposure to water may cause the HV battery to produce heat, resulting in a fire.

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

(a) Connect the Techstream to the DLC3.

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

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

(d) Check for DTCs.

(e) Turn the power switch off.

B

GO TO DTC CHART (HYBRID CONTROL SYSTEM)

A

(a) Connect the Techstream to the DLC3.

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

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

(d) Read output DTCs.

(e) Using the Techstream, make a note of the freeze frame data item "Hybrid Battery Block 3 to 8 Voltage".

(f) Compare the freeze frame data item "Hybrid Battery Block 3 to 8 Voltage" values with those shown in the following combination tables.

(g) Turn the power switch off.

B

GO TO STEP 5

A

(a) Read the odometer to check the total distance the vehicle has been driven.

HINT:

*1: If the hybrid battery terminal block has been replaced, use the total distance driven since it was replaced.

A

REPLACE HV BATTERY

B

Click here

NEXT

REPLACE HYBRID BATTERY TERMINAL BLOCK

(a) Connect the Techstream to the DLC3.

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

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

(d) Read output DTCs.

(e) Using the Techstream, make a note of the freeze frame data item "Hybrid Battery Block 1, 2, 9, 10 and 11 Voltage".

(f) Compare the freeze frame data item "Hybrid Battery Block 1, 2, 9, 10 and 11 Voltage" values with those shown in the following combination tables.

HINT:

If an internal malfunction occurs in the battery voltage sensor, this symptom (difference in voltage of 1.2 V or more for certain pairs of blocks as shown in the illustration) will occur.

(g) Turn the power switch off.

A

REPLACE BATTERY VOLTAGE SENSOR

B

(a) Read the odometer to check the total distance the vehicle has been driven.

HINT:

*1: If the hybrid battery terminal block has been replaced, use the total distance driven since it was replaced.

A

REPLACE HV BATTERY

B

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NEXT

REPLACE HYBRID BATTERY TERMINAL BLOCK