What is the hybrid battery sensor module?

It's the unit that monitors the HV battery's voltage, current, and temperature (and cooling-fan frequency) and reports to the power management control ECU. U029A means that report has stopped reaching the ECU.

Will U029A leave me stranded?

It can. Without trusted battery data the hybrid system may limit function or refuse to enter Ready, so it's best fixed before it progresses.

Is U029A a wiring or a module problem?

Most often wiring, a connector, or power/ground on the communication path — those are checked before replacing the battery sensor module or the ECU.

Can I diagnose U029A myself?

Reading codes and checking wiring is fine, but any hands-on work on the high-voltage battery requires proper HV safety procedures and training.

U029A Toyota Highlander – Lost Communication with Hybrid Battery Pack Sensor Module

U0073 Sending Malfunction (Navigation to APGS)
U0100 Engine ECU Communication
U0101 Lost Communication with TCM
U0103 Lost Communication with Gear Shift Module "A"
U0104 Lost Communication with Driving Support ECU
U0110 Lost Communication with Drive Motor Control Module "A"
U0114 Lost Communication with 4WD Control ECU
U011B Lost Communication with Rocker Arm Control Module "A"

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