The coolant pump is usually located at the top or in front of the engine. It is activated by the PCM via a voltage signal. The Powertrain Control Module receives inputs of voltages resulting from coolant temperature, air conditioning pressure sensors, engine speed, and intake temperature. They are used to calculate the time required for pump operation. Once the PCM has this data, the pump signal is modified as necessary.
The P261A OBD2 fault code is set when the PCM detects an open circuit in the coolant pump, which means a malfunction of the circuit.