RADIATOR FAN RELAY
The radiator fan relay is a solid state type and is located under the left front headlamp module Radiator Fan Relay Refer to WIRING DIAGRAMS for a circuit schematic.
The solid state radiator fan relay is controlled by the Powertrain Control Module (PCM) by way of a Pulse Width Modulated (PWM) signal. The relay control circuit supplies a 12 volt signal to the PCM. The PCM then pulses the ground circuit to achieve fan on time. The relay provides a voltage to the fan motors which is proportional to the pulse width it receives from the PCM. The duty cycle ranges from 30% for low speed operation, then ramps-up to 100% for high speed operation. This fan control system provides infinitely variable fan speeds, allowing for improved fan noise, A/C performance, better engine cooling, and additional vehicle power.
To control operation of the relay, the PCM looks at inputs from:
•Engine coolant temperature
•A/C pressure transducer
•Ambient temperature from the body controller
•Transmission oil temperature
The PCM uses these inputs to determine when the fan should operate and at what speed. Refer to Specifications - Radiator Fan Operation in this section.