DTC U029A-123: Lost Communication with Hybrid Battery Pack Sensor Module: Procedure

CHECK DTC OUTPUT (HV)

Connect the Techstream to the DLC3.
Turn the power switch on (IG).
Enter the following menus: Powertrain / Hybrid Control / Trouble Codes.

Check for DTCs. Refer to DTC CHECK / CLEAR .

Result

Result	Proceed to
Only U029A-123 is output.	A
DTCs other than U029A-123 are also output.	B

Disconnect the Techstream from the DLC3.

B → See step 6

A: Go to next step

CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU - BATTERY SMART UNIT)

WARNING:

Be sure to wear insulated gloves.

Disconnect the cable from the negative (-) battery terminal of the auxiliary battery.
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 repair information because this may cause a malfunction.
Disconnect connector H3 from the power management control ECU. Refer to REMOVAL .
Disconnect connector i1 from the battery smart unit.

Fig 1: Identifying i1 Connector Terminals
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

Fig 2: Identifying H3 Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Standard Resistance

Tester Connection	Switch Condition	Specified Condition
H3-32 (BTH+) - i1-2 (BTH+)	Power switch off	Below 1 Ω
H3-33 (BTH-) - i1-3 (BTH-)	Power switch off	Below 1 Ω
i1-2 (BTH+) - i1-8 (GND) and Body ground	Power switch off	10 kΩ or higher
i1-3 (BTH-) - i1-8 (GND) and Body ground	Power switch off	10 kΩ or higher

TEXT IN ILLUSTRATION

*a	Rear view of wire harness connector (to Power Management Control ECU)
*b	Rear view of wire harness connector (to Battery Smart Unit)

Remove the IGCT No. 2 fuse and AM2 fuse from the engine room junction block assembly.

Fig 3: Identifying IGCT No. 2 fuse and AM2 fuse

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

TEXT IN ILLUSTRATION

*1	Engine Room Junction Block Assembly
*2	AM2 Fuse
*3	IGCT No. 2 Fuse

Disconnect all connectors from the power management control ECU.

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

Fig 4: Identifying A19, A20, H3 And H4 Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Standard Resistance

Tester Connection	Switch Condition	Specified Condition
H3-32 (BTH+) - H4-7 (AM21)	Power switch off	10 kΩ or higher
H3-32 (BTH+) - H3-1 (AM22)	Power switch off	10 kΩ or higher
H3-32 (BTH+) - A19-2 (+B2)	Power switch off	10 kΩ or higher
H3-32 (BTH+) - A20-5 (+B1)	Power switch off	10 kΩ or higher
H3-32 (BTH+) - A20-6 (MREL)	Power switch off	10 kΩ or higher
H3-32 (BTH+) - A20-1 (IG2)	Power switch off	10 kΩ or higher
H3-32 (BTH+) - H4-1 (ACCD)	Power switch off	10 kΩ or higher
H3-32 (BTH+) H4-2 (IG1D)	Power switch off	10 kΩ or higher
H3-32 (BTH+) - A20-2 (IG2D)	Power switch off	10 kΩ or higher
H3-32 (BTH+) - A19-4 (FCTL)	Power switch off	10 kΩ or higher
H3-32 (BTH+) - H3-14 (SPDI)	Power switch off	10 kΩ or higher
H3-32 (BTH+) - A19-16 (GI)	Power switch off	10 kΩ or higher
H3-33 (BTH-) - H4-7 (AM21)	Power switch off	10 kΩ or higher
H3-33 (BTH-) - H3-1 (AM22)	Power switch off	10 kΩ or higher
H3-33 (BTH-) - A19-2 (+B2)	Power switch off	10 kΩ or higher
H3-33 (BTH-) - A20-5 (+B1)	Power switch off	10 kΩ or higher
H3-33 (BTH-) - A20-6 (MREL)	Power switch off	10 kΩ or higher
H3-33 (BTH-) - A20-1 (IG2)	Power switch off	10 kΩ or higher
H3-33 (BTH-) - H4-1 (ACCD)	Power switch off	10 kΩ or higher
H3-33 (BTH-) - H4-2 (IG1D)	Power switch off	10 kΩ or higher
H3-33 (BTH-) - A20-2 (IG2D)	Power switch off	10 kΩ or higher
H3-33 (BTH-) - H3-14 (SPDI)	Power switch off	10 kΩ or higher
H3-33 (BTH-) - A19-4 (FCTL)	Power switch off	10 kΩ or higher
H3-33 (BTH-) - A19-16 (GI)	Power switch off	10 kΩ or higher

TEXT IN ILLUSTRATION

Rear view of wire harness connector
(to Power Management Control ECU)

NOTE:

When taking a measurement with a tester, do not apply excessive force to the tester probe to avoid damaging the holder.

Connect the cable to the negative (-) battery terminal of the auxiliary battery.
Connect the battery smart unit connector.
Connect the power management control ECU connectors. Refer to INSTALLATION .

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to next step

CHECK POWER MANAGEMENT CONTROL ECU

WARNING:

Be sure to wear insulated gloves.

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 repair information because this may cause a malfunction.
Disconnect connector i1 from the battery smart unit.

Fig 5: Identifying i1 Connector Terminals
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Turn the power switch on (IG).

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

NOTE:

Turning the power switch on (IG) with the service plug grip removed causes an interlock switch system DTC to be set. Use the Techstream to clear the DTCs. Refer to DTC CHECK / CLEAR .

Fig 6: Identifying i1 Connector Terminals

Standard Voltage

Tester Connection	Switch Condition	Specified Condition
i1-2 (BTH+) - i1-8 (GND)	Power switch on (IG)	2.3 to 2.7 V
i1-3 (BTH-) - i1-8 (GND)	Power switch on (IG)	2.3 to 2.7 V

TEXT IN ILLUSTRATION

*a	Rear view of wire harness connector (to Battery Smart Unit)

Turn the power switch off.

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

Fig 7: Identifying i1 Connector Terminals

Standard Resistance

Tester Connection	Switch Condition	Specified Condition
i1-2 (BTH+) - i1-3 (BTH-)	Power switch off	4.4 to 5.4 kΩ

TEXT IN ILLUSTRATION

*a	Rear view of wire harness connector (to Battery Smart Unit)

HINT:

Resistance becomes 2.0 kΩ or less when there is a short circuit in the power management control ECU.

Connect the battery smart unit connector.

NG → See step 5

OK → See step 4

REPLACE BATTERY SMART UNIT. Refer to COMPONENTS
REPLACE POWER MANAGEMENT CONTROL ECU. Refer to COMPONENTS
GO TO DTC CHART. Refer to DIAGNOSTIC TROUBLE CODE CHART