DSD Information System
Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 61 (Hybrid Control System (2WD) - Diagnostic Codes (7 Of 7) & Circuit Tests) >> HYBRID CONTROL SYSTEM (for 2WD) >> DTC U029A-87: Lost Communication with Hybrid/EV Battery Sensor Module Missing Message [12/2019 - 11/2023] >> Procedure

DTC U029A-87: Lost Communication with Hybrid/EV Battery Sensor Module Missing Message [12/2019 - 11/2023]: Procedure

WARNING: This page is about a different variant/trim than selected.
  1. CHECK DTC OUTPUT (HYBRID CONTROL) 
    1. Check and record any Hybrid 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
    2. Turn the ignition switch off.

    Result: 

    B 

    GO TO DTC CHART (HYBRID CONTROL SYSTEM). Refer to  DIAGNOSTIC TROUBLE CODE CHART [12/2019 - 09/2020]  , or refer to  DIAGNOSTIC TROUBLE CODE CHART [09/2020 - 10/2021]  , or refer to  DIAGNOSTIC TROUBLE CODE CHART [10/2021 - 11/2023] 

    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 ignition switch to ON (READY), unless instructed by the repair information because this may cause a malfunction.

    2. Remove the No. 1 hybrid battery shield sub-assembly.

      Refer to REMOVAL [12/2019 - 10/2022] , or refer to REMOVAL [10/2022 - 11/2023]

    3. Connect the cable to the negative (-) auxiliary battery terminal.
    4. Turn the ignition switch to ON.
    5. Measure the voltage according to the value(s) in the table below.
      GTY863228Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Battery Voltage Sensor)

      Standard Voltage

      Tester Connection Condition Specified Condition
      y1-1 (IGCT) - y1-7 (GND) Ignition switch ON 11 to 14 V
      NOTE:

      Turning the ignition switch to ON 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 ignition switch off.
    7. Disconnect the cable from the negative (-) auxiliary battery terminal.
    8. Install the No. 1 hybrid battery shield sub-assembly.

      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 ignition switch to ON (READY), unless instructed by the repair information because this may cause a malfunction.

    2. Disconnect the A32 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 shield sub-assembly.

      Refer to REMOVAL [12/2019 - 10/2022] , or refer to REMOVAL [10/2022 - 11/2023]

    4. Disconnect the y1 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
      A32-9 (CA4H) - y1-2 (CA1H) Ignition switch off Below 1 Ω
      A32-22 (CA4L) - y1-3 (CA1L) Ignition switch off Below 1 Ω
      y1-2 (CA1H) - Body ground and other terminals Ignition switch off 10 kΩ or higher
      y1-3 (CA1L) - Body ground and other terminals Ignition switch off 10 kΩ or higher
      GTY840973Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front 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. Reconnect the y1 battery voltage sensor connector.
    7. Install the No. 1 hybrid battery shield sub-assembly.
    8. Reconnect the A32 hybrid vehicle control ECU connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE BATTERY VOLTAGE SENSOR. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

Diesel-Data.com