The blower motor is controlled by the blower control module. The blower control module receives the requested blower speed from the heater and A/C programmer (HCM) in the form of a 5 volt pulse modulated reference signal. When low speed is requested by the HCM, the pulse width is reduced. When high blower speed is requested, the pulse width is increased. An open circuit, short to ground or short to battery on the blower speed input circuit of the blower control module will disrupt the pulse modulated reference signal. If the blower control module does not receive the pulse modulated signal, the blower motor will not operate. The blower control module receives power from the underhood fuse block. The blower control module also provides a ground for the blower motor.