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Home >> Lexus >> 2020 >> ES 300h Luxury >> Repair and Diagnosis >> Hybrid/Electric Powertrain >> Testing and Diagnosis >> Hybrid Control System (For Nickel Metal Hydride Battery) - Diagnostic Codes (5 Of 5) & Circuit Tests (1 Of 2) >> HYBRID CONTROL SYSTEM (for NICKEL METAL HYDRIDE BATTERY) >> DTC U029A-87: Lost Communication with Hybrid/EV Battery Sensor Module Missing Message [06/2018 - ] >> Procedure

DTC U029A-87: Lost Communication with Hybrid/EV Battery Sensor Module Missing Message [06/2018 - ]: Procedure

  1. CHECK DTC OUTPUT (HYBRID CONTROL) 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG).
    3. Enter the following menus: Powertrain / Hybrid Control / Trouble Codes.
    4. Check and record any HV system DTCs and freeze frame data. Check for DTCs.

      Powertrain > Hybrid Control > Trouble Codes 

      Result

      Result Proceed to
      Only "U029A-87" is output. A
      DTCs other than "U029A-87" are also output. B
    5. Turn the power switch off.

    Result: 

    B 

    GO TO DTC CHART (HYBRID CONTROL SYSTEM). Refer to  DIAGNOSTIC TROUBLE CODE CHART [06/2018 - 08/2021]  , or refer to  DIAGNOSTIC TROUBLE CODE CHART [08/2021 - ] 

    Result: 

    A 

    See step  2

  2. CHECK BATTERY VOLTAGE SENSOR (IGCT VOLTAGE) 
    WARNING:

    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 appropriate service information because this may cause a malfunction.

    2. Remove the No. 1 hybrid battery exhaust duct.

      Refer to PROCEDURE - Step 14 [06/2018 - 08/2021] , or refer to PROCEDURE - Step 14 [08/2021 - 09/2022] , or refer to PROCEDURE - Step 14 [09/2022 - ]

    3. Connect the cable to the negative (-) auxiliary battery terminal.
    4. Turn the power switch on (IG).
    5. Measure the voltage according to the value(s) in the table below.
      GTY797025Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Battery Voltage Sensor)

      Standard Voltage

      Tester Connection Condition Specified Condition
      N21-1 (IGCT) - N21-5 (GND) Power switch on (IG) 11 to 14 V
      NOTE:

      Turning the power switch on (IG) with the service plug grip removed causes other DTCs to be stored. Clear the DTCs after performing this inspection.

      HINT: 

      As there might be an intermittent malfunction in the battery voltage sensor power source circuit, inspect the following even if the measured voltage is as specified:

      • Installation condition of fuse(s) (before removing fuse(s)) (IGCT circuit)
      • Fuse condition (before and after removing fuse(s)) (IGCT circuit)
      • Connection condition of connectors (IGCT circuit)
      • Wire harness condition (IGCT circuit)
      • Wire harness condition (GND circuit)
    6. Turn the power switch off.
    7. Disconnect the cable from the negative (-) auxiliary battery terminal.
    8. Install the No. 1 hybrid battery exhaust duct.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY VOLTAGE SENSOR POWER SOURCE CIRCUIT) 

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - BATTERY VOLTAGE SENSOR) 
    WARNING:

    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 appropriate service information because this may cause a malfunction.

    2. Disconnect the G59 hybrid vehicle control ECU connector.
      NOTE:
      • Before disconnecting the connector, check that it is not loose or disconnected.
      • Check that each connector between the hybrid vehicle control ECU and battery voltage sensor is not loose or disconnected.
    3. Remove the No. 1 hybrid battery exhaust duct.

      Refer to PROCEDURE - Step 14 [06/2018 - 08/2021] , or refer to PROCEDURE - Step 14 [08/2021 - 09/2022] , or refer to PROCEDURE - Step 14 [09/2022 - ]

    4. Disconnect the N21 battery voltage sensor connector.
      NOTE:
      • Before disconnecting the connector, check that it is not loose or disconnected.
      • Check the terminals of the connector for deformation and corrosion.
    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      G59-32 (BTH+) - N21-2 (BTH+) Power switch off Below 1 Ω
      G59-33 (BTH-) - N21-3 (BTH-) Power switch off Below 1 Ω
      N21-2 (BTH+) - Other terminals and body ground Power switch off 10 kΩ or higher
      N21-3 (BTH-) - Other terminals and body ground Power switch off 10 kΩ or higher
      GTY785194Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Rear view of wire harness connector
      (to Hybrid Vehicle Control ECU)
      *b Rear view of wire harness connector
      (to Battery Voltage Sensor)
      NOTE:

      Make sure that each connector between the battery voltage sensor and hybrid vehicle control ECU is not loose or disconnected and its terminals are not deformed or corroded.

    6. Connect the cable to the negative (-) auxiliary battery terminal.
    7. Turn the power switch on (IG).
    8. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      G59-32 (BTH+) - Body ground Power switch on (IG) Below 1 V
      G59-33 (BTH-) - Body ground Power switch on (IG) Below 1 V
      NOTE:
      • Turning the power switch on (IG) with the service plug grip removed causes other DTCs to be stored. Clear the DTCs after performing this inspection.
      • If the power switch is turned on (IG) with the connectors disconnected, other DTCs will be stored. Be sure to clear the DTCs after the inspection.
    9. Turn the power switch off.
    10. Disconnect the cable from the negative (-) auxiliary battery terminal.
    11. Reconnect the N21 battery voltage sensor connector.
    12. Install the No. 1 hybrid battery exhaust duct.
    13. Reconnect the G59 hybrid vehicle control ECU connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. CHECK HYBRID VEHICLE CONTROL ECU 
    WARNING:

    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 appropriate service information because this may cause a malfunction.

    2. Remove the No. 1 hybrid battery exhaust duct.

      Refer to PROCEDURE - Step 14 [06/2018 - 08/2021] , or refer to PROCEDURE - Step 14 [08/2021 - 09/2022] , or refer to PROCEDURE - Step 14 [09/2022 - ]

    3. Disconnect the N21 battery voltage sensor connector.
      NOTE:

      Before disconnecting the connector, check that it is not loose or disconnected.

    4. Connect the cable to the negative (-) auxiliary battery terminal.
    5. Turn the power switch on (IG).
    6. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      N21-2 (BTH+) - N21-5 (GND) Power switch on (IG) 2.3 to 2.7 V
      N21-3 (BTH-) - N21-5 (GND) Power switch on (IG) 2.3 to 2.7 V
      GTY787227Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Rear view of wire harness connector
      (to Battery Voltage Sensor)
      NOTE:
      • Turning the power switch on (IG) with the service plug grip removed causes other DTCs to be stored. Clear the DTCs after performing this inspection.
      • If the power switch is turned on (IG) with the connectors disconnected, other DTCs will be stored. Be sure to clear the DTCs after the inspection.
    7. Turn the power switch off.
    8. Disconnect the cable from the negative (-) auxiliary battery terminal.
    9. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      N21-2 (BTH+) - N21-3 (BTH-) Power switch off 4.4 to 5.4 kΩ

      HINT: 

      The resistance will be 2.0 kΩ or less if there is an internal short in the hybrid vehicle control ECU.

    10. Reconnect the N21 battery voltage sensor connector.
    11. Install the No. 1 hybrid battery exhaust duct.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE BATTERY VOLTAGE SENSOR. Refer to  REMOVAL [06/2018 - 08/2021]  , or refer to  REMOVAL [08/2021 - 09/2022]  , or refer to  REMOVAL [09/2022 - ] 

    Result: 

    NG 

    REPLACE HYBRID VEHICLE CONTROL ECU. Refer to  REMOVAL [06/2018 - 08/2021]  , or refer to  REMOVAL [08/2021 - 09/2022]  , or refer to  REMOVAL [09/2022 - ] 

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