HYBRID BATTERY SYSTEM, Diagnostic DTC:U029A-123

DTC Code DTC Name
U029A-123 Lost Communication with Hybrid Battery Pack Sensor Module

DESCRIPTION

The battery smart unit detects the HV battery conditions (voltage, current, and temperature) and the battery cooling fan voltage, and sends the detected information to the hybrid vehicle control ECU.

DTC Code DTC Detection Condition Trouble Area
U029A-123 A communication error between the battery smart unit and hybrid vehicle control ECU (1 trip detection)

  • Harness or connector

  • Auxiliary battery

  • Hybrid vehicle control ECU

  • Battery smart unit

  • IGCT3 fuse

  • IGCT2 NO. 2 fuse

  • ST CUT / IGCT2 relay

WIRING DIAGRAM

A01H19UE02

INSPECTION PROCEDURE

CAUTION:


  • Before inspecting the high-voltage system, take safety precautions such as wearing insulated gloves and removing the service plug grip to prevent electrical shocks. After removing the service plug grip, put it in your pocket to prevent other technicians from accidentally reconnecting it while you are working on the high-voltage system.

  • After disconnecting 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.

Tech Tips

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

PROCEDURE


  1. CHECK WAVEFORM

    CAUTION:

    Be sure to wear insulated gloves.


    1. A01GZLZE04

      Connect an oscilloscope to the hybrid vehicle control ECU and battery smart unit terminals specified in the table below and measure the waveform.

      Item Contents
      Terminal

      CH1: A78-20 (BTH+) - E58-7 (GND1)

      CH2: A78-19 (BTH-) - E58-7 (GND1)
      Equipment Setting 2 V/DIV, 500 μs/DIV
      Condition Power switch on (IG)
      OK
      The waveform appears as shown in the illustration.

    NG

    CHECK AUXILIARY BATTERY Click here

    OK

    REPLACE HYBRID VEHICLE CONTROL ECU Click here

  2. CHECK AUXILIARY BATTERY


    1. Turn the power switch off.

    2. Measure the voltage between the terminals of the auxiliary battery.

      Standard Voltage
      Tester Connection Condition Specified Condition
      Auxiliary battery positive (+) terminal - Auxiliary battery negative (-) terminal Battery electrolyte temperature: 20°C (68°F) 11 to 14 V

    NG

    CHARGE OR REPLACE AUXILIARY BATTERY

    OK

  3. CHECK HARNESS AND CONNECTOR (IGCT VOLTAGE)


    1. Turn the power switch on (IG).

    2. A01H1QFE01

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      zR3-3 (IGCT) - zR3-16 (GND) Power switch on (IG) 11 to 14 V

      Tech Tips


      • For the removal and installation procedures related to the No. 1 battery pack wire inspection, Click here.

      • Perform this inspection with the No. 1 battery pack wire connected.


    NG

    Click here

    OK

  4. CHECK HARNESS AND CONNECTOR (NO. 1 BATTERY PACK WIRE CONNECTOR [A SIDE] - HYBRID VEHICLE CONTROL ECU)


    1. Disconnect the zR3 No. 1 battery pack wire connector.

      A01H16YE02

      Tech Tips

      For the removal and installation procedures related to the No. 1 battery pack wire connector inspection, Click here.

    2. Disconnect the A78 hybrid vehicle control ECU connector.

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

      Standard Resistance (Check for open)
      Tester Connection Switch Condition Specified Condition
      A78-20 (BTH+) - zR3-13 (BTH+) Power switch off Below 1 Ω
      A78-19 (BTH-) - zR3-12 (BTH-) Power switch off Below 1 Ω
      Standard Resistance (Check for short)
      Tester Connection Switch Condition Specified Condition
      A78-20 (BTH+) - Body ground and other terminals Power switch off 10 kΩ or higher
      A78-19 (BTH-) - Body ground and other terminals Power switch off 10 kΩ or higher

    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage (Check for +B short)
      Tester Connection Switch Condition Specified Condition
      A78-20 (BTH+) - Body ground Power switch on (IG) Below 1 V
      A78-19 (BTH-) - Body ground Power switch on (IG) Below 1 V

      Tech Tips

      If the power switch is turned on (IG) under the conditions above, DTCs may be stored. In this case, use the intelligent tester to clear the DTCs Click here.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. CHECK HARNESS AND CONNECTOR (NO. 1 BATTERY PACK WIRE CONNECTOR [B SIDE] - BATTERY SMART UNIT)

    CAUTION:

    Be sure to wear insulated gloves.


    1. A01H23ME02

      Remove the HV battery Click here.

    2. Disconnect the z36 battery smart unit connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      z36-1 (IGCT) - zR3-3 (IGCT) Always Below 1 Ω
      z36-5 (GND) - zR3-16 (GND) Always Below 1 Ω
      z36-2 (BTH+) - zR3-13 (BTH+) Always Below 1 Ω
      z36-3 (BTH-) - zR3-12 (BTH-) Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. REPLACE BATTERY SMART UNIT

    Tech Tips

    For the removal and installation procedures related to the battery smart unit, Click here.


    NEXT

  7. CLEAR DTC (HV)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG).

    3. Select the following menu items: Powertrain / Hybrid Control / Trouble Codes.

    4. Clear DTCs and freeze frame data.


    NEXT

  8. RECONFIRM DTC OUTPUT (HV)


    1. Select the following menu items: Powertrain / Hybrid Control / Trouble Codes.

    2. Check if DTCs are output.

      Result
      Result Proceed to
      P029A-123 is output. A
      No DTCs are output. B

    B

    END (BATTERY SMART UNIT IS FAULTY)

    A

    REPLACE HYBRID VEHICLE CONTROL ECU Click here

  9. CHECK FUSE (IGCT3)


    1. A01GZIOE02

      Turn the power switch off.

    2. Remove the IGCT3 fuse from the luggage room junction block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      IGCT3 fuse Always Below 1 Ω

    NG

    REPLACE FUSE (IGCT3)

    OK

  10. CHECK FUSE (IGCT NO. 2)


    1. A01GW45E05

      Remove the IGCT2 NO. 2 fuse from the engine room No. 3 relay block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      IGCT2 NO. 2 fuse Always Below 1 Ω

    NG

    REPLACE FUSE (IGCT NO. 2)

    OK

  11. INSPECT RELAY (ST CUT / IGCT2)


    1. A01H1JXE02

      Remove the ST CUT / IGCT2 relay from the engine room No. 2 relay block.

    2. A01GZ8X

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3 - 5 Battery voltage is applied between terminals 1 and 2. Below 1 Ω
      Battery voltage is not applied between terminals 1 and 2. 10 kΩ or higher

    NG

    REPLACE RELAY (ST CUT / IGCT2)

    OK

  12. CHECK HARNESS AND CONNECTOR (NO. 1 BATTERY PACK WIRE CONNECTOR [A SIDE] - ST CUT / IGCT2 RELAY)

    CAUTION:

    Be sure to wear insulated gloves.


    1. Disconnect the No. 1 battery pack wire connector.

    2. Install the IGCT3 fuse to the luggage room junction block.

    3. Install the IGCT2 NO. 2 fuse to the engine room No. 3 relay block.

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

      A01GX7VE02
      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      zR3-3 (IGCT) - ST CUT / IGCT2 relay terminal 3 Power switch off Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    CHECK AND REPAIR POWER SOURCE CIRCUIT (ST CUT / IGCT2 RELAY POWER SOURCE)