Lexus ES manuals

Lexus ES: Lost Communication with Hybrid/EV Battery Sensor Module Missing Message (U029A87)

Lexus ES (XZ10) Service Manual / Engine & Hybrid System / Hybrid / Battery Control / Hybrid Control System (for Nickel Metal Hydride Battery) / Lost Communication with Hybrid/EV Battery Sensor Module Missing Message (U029A87)

DESCRIPTION

The battery voltage sensor detects the HV battery conditions (voltage, current and temperature) and the battery cooling fan frequency, and sends the detected signals to the hybrid vehicle control ECU via serial communication. (The hybrid vehicle control ECU does not send signals to the battery voltage sensor.)

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Warning Indicate

U029A87

Lost Communication with Hybrid/EV Battery Sensor Module Missing Message

Serial communication error between the hybrid vehicle control ECU and battery voltage sensor: The hybrid vehicle control ECU cannot receive signals from the battery voltage sensor correctly.

(1 trip detection logic)
  • Hybrid vehicle control ECU
  • Battery voltage sensor
  • Wire harness or connector

Comes on

Master Warning Light:

Comes on

MONITOR DESCRIPTION

If a malfunction in communication line between the battery voltage sensor and hybrid vehicle control ECU is detected, the hybrid vehicle control ECU will illuminate the MIL and store a DTC.

MONITOR STRATEGY

Related DTCs

U029A (INF U029A87): Battery voltage sensor communication malfunction

Required sensors/components

Main: Battery voltage sensor

Sub: Communication line

Frequency of operation

Continuous

Duration

TMC's intellectual property

MIL operation

Immediately

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

Battery voltage sensor

DTC U029A (INF U029A87) 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. With power switch on (IG) and wait for 2 minutes or more. [*1]

    HINT:

    [*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 DTC P0AFC00.

Click here

CAUTION / NOTICE / HINT

CAUTION:

  • Before inspecting the high-voltage system, take safety precautions to prevent electrical shocks, such as wearing insulated gloves and removing the service plug grip. 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.
    • 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.

Click here

PROCEDURE

1.

CHECK DTC OUTPUT (HYBRID CONTROL)

(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 and record any HV system DTCs and freeze frame data. Check for DTCs.

Powertrain > Hybrid Control > Trouble Codes

Result

Proceed to

Only "U029A87" is output.

A

DTCs other than "U029A87" are also output.

B

(e) Turn the power switch off.

B

GO TO DTC CHART (HYBRID CONTROL SYSTEM)

A

2.

CHECK BATTERY VOLTAGE SENSOR (IGCT VOLTAGE)

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 hybrid battery exhaust duct.

Click here

(c) Connect the cable to the negative (-) auxiliary battery terminal.

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

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

N21-1 (IGCT) - N21-5 (GND)

Power switch on (IG)

11 to 14 V

NOTICE:

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)

*a

Component with harness connected

(Battery Voltage Sensor)

(f) Turn the power switch off.

(g) Disconnect the cable from the negative (-) auxiliary battery terminal.

(h) Install the No. 1 hybrid battery exhaust duct.

NG

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

3.

CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - BATTERY VOLTAGE SENSOR)

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) Disconnect the G59 hybrid vehicle control ECU connector.

NOTICE:

  • 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.

(c) Remove the No. 1 hybrid battery exhaust duct.

Click here

(d) Disconnect the N21 battery voltage sensor connector.

NOTICE:

  • Before disconnecting the connector, check that it is not loose or disconnected.
  • Check the terminals of the connector for deformation and corrosion.

(e) 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

NOTICE:

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.

*a

Rear view of wire harness connector

(to Hybrid Vehicle Control ECU)

*b

Rear view of wire harness connector

(to Battery Voltage Sensor)

(f) Connect the cable to the negative (-) auxiliary battery terminal.

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

(h) 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

NOTICE:

  • 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.

(i) Turn the power switch off.

(j) Disconnect the cable from the negative (-) auxiliary battery terminal.

(k) Reconnect the N21 battery voltage sensor connector.

(l) Install the No. 1 hybrid battery exhaust duct.

(m) Reconnect the G59 hybrid vehicle control ECU connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

4.

CHECK HYBRID VEHICLE CONTROL ECU

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 hybrid battery exhaust duct.

Click here

(c) Disconnect the N21 battery voltage sensor connector.

NOTICE:

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

(d) Connect the cable to the negative (-) auxiliary battery terminal.

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

(f) 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

NOTICE:

  • 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.

*a

Rear view of wire harness connector

(to Battery Voltage Sensor)

(g) Turn the power switch off.

(h) Disconnect the cable from the negative (-) auxiliary battery terminal.

(i) 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.

(j) Reconnect the N21 battery voltage sensor connector.

(k) Install the No. 1 hybrid battery exhaust duct.

OK

REPLACE BATTERY VOLTAGE SENSOR

NG

REPLACE HYBRID VEHICLE CONTROL ECU

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