DTC P0516-769: Battery Temperature Sensor Circuit Low; DTC P0517-770: Battery Temperature Sensor Circuit High: Description

The battery thermometer sensor detects the auxiliary battery temperature. The resistance of the thermistor built into the battery thermometer sensor changes in accordance with changes in the auxiliary battery temperature. The lower the auxiliary battery temperature, the higher the battery thermometer sensor resistance. Conversely, the higher the temperature, the lower the resistance. The battery thermometer sensor is connected to the hybrid vehicle control ECU. A voltage of 5 V is supplied to the battery thermometer sensor from the THB terminal of the hybrid vehicle control ECU through its internal resistor R. This means that resistor R and the battery thermometer sensor are connected in series. The voltage at the THB terminal and the resistance value change in accordance with changes in the auxiliary battery temperature. Based on this signal, the hybrid vehicle control ECU reduces the charging current when the auxiliary battery temperature is high to protect the auxiliary battery.

Fig 1: Identifying THB Terminal Resistance To Temperature Graph
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

DTC No.	INF Code	DTC Detection Condition	Trouble Area
P0516	769	Malfunction in the auxiliary battery thermometer sensor circuit (short to GND)	Battery thermometer sensor Wire harness or connector Hybrid vehicle control ECU
P0517	770	Malfunction in the auxiliary battery thermometer sensor circuit (open or +B short circuit)	Battery thermometer sensor Wire harness or connector Hybrid vehicle control ECU