DTC P0A81-11: Hybrid/EV Battery Cooling Fan 1 Circuit Short to Ground; DTC P0A81-4B: Hybrid/EV Battery Cooling Fan 1 Over Temperature [09/2023 - ]: Description

WARNING: This page is about a different car, the 2024 Lexus TX 500h. However, it is still accessible from the selected car via links, so may be relevant.

The battery cooling blower assembly speed is controlled by the battery voltage sensor. Power is supplied to the battery cooling blower assembly when the MREL terminal of the hybrid vehicle control ECU assembly turns on the IGCT NO. 1 relay. The battery voltage sensor 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 frequency (FP0) of the battery cooling blower assembly is sent to the hybrid vehicle control ECU assembly via the battery voltage sensor as a monitor signal using CAN communication.

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DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Warning Indicate	DTC Output from	Priority	Note
P0A81-11	Hybrid/EV Battery Cooling Fan 1 Circuit Short to Ground	Both of the following conditions are met: The speed calculated based on the battery cooling blower assembly output frequency is not within the target control speed range. The battery cooling blower assembly speed is excessively low when a certain level of speed is requested (possibility of an open or short to ground in connected circuits, or motor locking). (2 trip detection logic)	Battery voltage sensor Battery cooling blower assembly BATT FAN relay Wire harness or connector	Comes on	Master Warning: Comes on	Hybrid Control	A	SAE Code: P0A84
P0A81-4B	Hybrid/EV Battery Cooling Fan 1 Over Temperature	Both of the following conditions are met: The HV battery temperature is high and the speed calculated based on the battery cooling blower assembly output frequency is not within the target control speed range. The HV battery temperature is high and the battery cooling blower assembly speed is excessively low when a certain level of speed is requested (possibility of an open or short to ground in connected circuits, or motor locking). (1 trip detection logic)	Battery voltage sensor Battery cooling blower assembly BATT FAN relay Wire harness or connector	Comes on	Master Warning: Comes on	Hybrid Control	A	SAE Code: P0A84

HINT:

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