Grand Caravan FWD V6-3.8L VIN L (2001)
Radiator Cooling Fan Motor Relay: Description and Operation
DESCRIPTION
The radiator fan relay is a solid state type and is located on the front bumper reinforcement.
OPERATION
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
^
Vehicle speed
^
Transmission oil temperature
The PCM uses these inputs to determine when the fan should operate and at what speed.
OPERATION
