DTC U029A-87: Lost Communication with Hybrid/EV Battery Sensor Module Missing Message [09/2023 - ]: Procedure

Pre-procedure1

• None.

• Check and record any Hybrid System DTCs and Freeze Frame Data. Check for DTCs.

  Powertrain > Hybrid Control > Trouble Codes 

  Result

  Result	Proceed to
  Only U029A-87 is output	A
  U029A-87 and other DTCs are output	B

Post-procedure1

• Turn the ignition switch off.

Result: 

B 

GO TO DTC CHART (HYBRID CONTROL SYSTEM). Refer to  DIAGNOSTIC TROUBLE CODE CHART [09/2023 - ] 

Result: 

A 

See step  2

Pre-procedure1

• Check that the service plug grip is not installed.
  NOTE:

  After removing the service plug grip, do not turn the ignition switch to ON (READY), unless instructed by the service information because this may cause a malfunction.

• Connect the cable to the negative (-) auxiliary battery terminal.
• Turn the ignition switch to ON.

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

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

  *a	Component with harness connected (Battery Voltage Sensor)

  Standard Voltage

  Tester Connection	Condition	Specified Condition	Result
  z11-1 (IGCT) - z11-7 (GND)	Ignition switch ON	11 to 14 V	V

  NOTE:

  Turning the ignition switch to ON 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)

  Result

  Proceed to
  OK
  NG

Post-procedure1

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

Result: 

OK 

GO TO CAN COMMUNICATION SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [09/2023 - ] 

Result: 

NG 

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