The powertrain control module (PCM) commands the fans on in either high speed or low speed, depending on cooling requirements. In low speed, both fans are turned on at a reduced speed. High speed has both fans turned on at a higher speed.
In low speed operation, the PCM applies ground to the coil side of the COOL/FAN Relay 1. This energizes the coil and applies voltage to the left cooling fan through the switch side of the relay, which is fed by the COOL/FAN 1 fuse. After voltage has passed through the cooling fan 1, it continues through the COOLSER/PAR Relay, which acts as a series/parallel relay, controlling fan speed, a ground path is given through G101. In low speed, the COOLSER/PAR Relay passes voltage to the cooling fan 2, effectively operating both fans in a series circuit. From the cooling fan 2, a ground path is given through G111.
In high speed operation, the PCM applies a ground to the coil side of the COOL/FAN Relay 1, COOL/FAN Relay 2, and COOLSER/PAR Relay. On the COOL/FAN Relay 2, the energized coil closes the switch side of the relay and applies voltage to the cooling fan 2. The energized COOLSER/PAR pulls the switch side over, providing a direct path to ground for the cooling fan 1, which has voltage applied through the energized COOL/FAN Relay 1. In high speed mode, the fans are operated as a parallel circuit with full voltage applied to each.