DTC P0A84-123: Hybrid Battery Pack Cooling Fan 1 Control Circuit Low [12/2014 - ]: Description

The speed of the battery cooling blower assembly is controlled by the hybrid vehicle control ECU. Power is supplied to the battery cooling blower assembly when the MREL terminal of the hybrid vehicle control ECU turns on the IGCT relay. The hybrid vehicle control ECU sends command signals SI0 to the battery cooling blower assembly to adjust the fan speed to an appropriate speed for the HV battery temperature. The battery cooling blower assembly frequency (FP) is sent to the hybrid vehicle control ECU via the battery smart unit as a monitor signal using serial communication.

Fig 1: Hybrid Battery Pack Cooling Fan Communication Diagram
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

DTC No.	INF Code	DTC Detection Condition	Trouble Area
P0A84	123	Both of the following conditions are met due to the battery cooling blower system malfunction: (1 trip detection logic) The speed calculated based on the battery cooling blower assembly output frequency (FP) is not within the target control speed range. The battery cooling blower assembly speed is excessively low when a certain level speed is requested (possibility of open or short to ground in connected circuits, short to +B or motor locking).	Wire harness or connector BATT FAN fuse Battery cooling blower assembly Battery smart unit Hybrid vehicle control ECU

RELATED DATA LIST

DTC No.	Data List
P0A84-123	Cooling Fan 0 Cooling Fan Mode 1 Cooling Fan Frequency 1

The following items can be helpful when performing repairs:

Data List

Temp of Batt TB1 to 3
+B

HINT:

"Cooling Fan Frequency 1" is detected when the battery cooling blower assembly is operating and its value changes in proportion to the battery cooling blower assembly rotation speed.