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

WARNING: This page is about a different variant/trim than selected.

CHECK DTC OUTPUT (HYBRID CONTROL)

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

Turn the power switch off.
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.

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 manual because this may cause a malfunction.
Disconnect connector I3 from the power management control ECU. Refer to REMOVAL .
Remove the rear side seat back assembly LH. Refer to REMOVAL - Step 9 .
Disconnect connector N18 from the battery smart unit.

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

Fig 1: Identifying I3 Power Management Control ECU And N18 Battery Smart Unit Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Standard Resistance

Tester Connection	Switch Condition	Specified Condition
I3-32 (BTH+) - N18-1 (BTH+)	Power switch off	Below 1 Ω
I3-33 (BTH-) - N18-4 (BTH-)	Power switch off	Below 1 Ω
N18-1 (BTH+) - N18-6 (GND) and Body ground	Power switch off	10 kΩ or higher
N18-4 (BTH-) - N18-6 (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 PM IGCT fuse from the No. 2 engine room relay block.

Fig 2: Identifying No. 2 Engine Room Relay Block And PM IGCT Fuse

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

TEXT IN ILLUSTRATION

*1	No. 2 Engine Room Relay Block
*2	PM IGCT fuse

Remove the AM2 fuse from the engine room relay block and junction block assembly.

Fig 3: Identifying Engine Room Relay Block & Junction Block Assembly And AM2 Fuse

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

TEXT IN ILLUSTRATION

*1	Engine Room Relay Block and Junction Block Assembly
*2	AM2 fuse

Remove the ECU-IG2 No. 1 fuse from the instrument panel junction block assembly.

Fig 4: Identifying Instrument Panel Junction Block Assembly And ECU-IG2 No. 1 Fuse

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

TEXT IN ILLUSTRATION

*1	Instrument Panel Junction Block Assembly
*2	ECU-IG2 NO. 1 fuse

Disconnect all connectors from the power management control ECU.

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

Fig 5: Identifying Power Management Control ECU Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Standard Resistance

Tester Connection	Switch Condition	Specified Condition
I3-32 (BTH+) - I4-7 (AM21)	Power switch off	10 kΩ or higher
I3-32 (BTH+) - I3-1 (AM22)	Power switch off	10 kΩ or higher
I3-32 (BTH+) - A38-2 (+B2)	Power switch off	10 kΩ or higher
I3-32 (BTH+) - A39-5 (+B1)	Power switch off	10 kΩ or higher
I3-32 (BTH+) - A39-6 (MREL)	Power switch off	10 kΩ or higher
I3-32 (BTH+) - A39-1 (IG2)	Power switch off	10 kΩ or higher
I3-32 (BTH+) - I4-1 (ACCD)	Power switch off	10 kΩ or higher
I3-32 (BTH+) I4-2 (IG1D)	Power switch off	10 kΩ or higher
I3-32 (BTH+) - A39-2 (IG2D)	Power switch off	10 kΩ or higher
I3-32 (BTH+) - I3-14 (SPDI)	Power switch off	10 kΩ or higher
I3-32 (BTH+) - A38-16 (GI)	Power switch off	10 kΩ or higher
I3-33 (BTH-) - I4-7 (AM21)	Power switch off	10 kΩ or higher
I3-33 (BTH-) - I3-1 (AM22)	Power switch off	10 kΩ or higher
I3-33 (BTH-) - A38-2 (+B2)	Power switch off	10 kΩ or higher
I3-33 (BTH-) - A39-5 (+B1)	Power switch off	10 kΩ or higher
I3-33 (BTH-) - A39-6 (MREL)	Power switch off	10 kΩ or higher
I3-33 (BTH-) - A39-1 (IG2)	Power switch off	10 kΩ or higher
I3-33 (BTH-) - I4-1 (ACCD)	Power switch off	10 kΩ or higher
I3-33 (BTH-) - I4-2 (IG1D)	Power switch off	10 kΩ or higher
I3-33 (BTH-) - A39-2 (IG2D)	Power switch off	10 kΩ or higher
I3-33 (BTH-) - I3-14 (SPDI)	Power switch off	10 kΩ or higher
I3-33 (BTH-) - A38-16 (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 battery smart unit connector.
Install the rear side seat back assembly LH.
Connect the power management control ECU connectors.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER MANAGEMENT CONTROL ECU - BATTERY SMART UNIT)

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 manual because this may cause a malfunction.
Remove the rear side seat back assembly LH. Refer to REMOVAL - Step 9 .
Disconnect connector N18 from the battery smart unit.
Connect the cable to the negative (-) auxiliary battery terminal.
Turn the power switch on (IG).

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

Fig 6: Identifying N18 Battery Smart Unit Connector Terminals

Standard Voltage

Tester Connection	Switch Condition	Specified Condition
N18-1 (BTH+) - N18-6 (GND)	Power switch on (IG)	2.3 to 2.7 V
N18-4 (BTH-) - N18-6 (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)

NOTE:

Turning the power switch on (IG) with the battery smart unit connector and power management control ECU connector disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

Turn the power switch off.
Disconnect the cable from the negative (-) auxiliary battery terminal.

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

Fig 7: Identifying N18 Battery Smart Unit Connector Terminals

Standard Resistance

Tester Connection	Switch Condition	Specified Condition
N18-1 (BTH+) - N18-4 (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.
Install the rear side seat back assembly LH.

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 (HYBRID BATTERY SYSTEM). Refer to DIAGNOSTIC TROUBLE CODE CHART