Circuit/System Description

When the park lamp switch is in the ON position, the instrument panel module (IPM) energizes the park lamp relay. With the park lamp relay energized, battery positive voltage is supplied through the DIMMING fuse to the instrument panel lamp fuse supply voltage circuit of the IPM. Upon receiving this voltage supply the IPM requests the status of the ambient light sensor from the climate control panel (CCP). The CCP sends a serial data message indicating a Light or Dark status of the ambient light sensor. The IPM will default to dark if the message is not received. If the status of the ambient light sensor is light, then the interior back lighting will not be activated. The IPM also receives an input from the instrument panel (I/P) dimmer switch. The IPM provides the I/P dimmer switch with a 5-volt reference voltage and ground. The I/P dimmer switch is a potentiometer that varies the input signal voltage to the IPM between 0.36-4.23 volts. This input determines the intensity level of the back lighting illumination. The driver may change intensity of the back lighting by positioning the I/P dimmer switch between the minimum and maximum settings. The IPM will default to full intensity if the input from the I/P dimmer switch is not within the specified values. Upon receipt of all the fore mentioned information, the IPM sends a serial data message to the CCP, IPC, radio, and all the door modules indicating the ON/OFF status and intensity level of the back lighting. The CCP, IPC, and radio incorporate vacuum fluorescent (VF) lamps that are illuminated at full intensity with the ignition in the ON position. The CCP, IPC, and radio will adjust the VF lamp intensity as requested by the IPM by varying the pulse width modulation of the power feed circuit to the VF lamps. When the door control modules receive the serial data message, each door module will supply pulse width modulation (PWM) voltage to the door switch LEDs at the requested intensity. The IPM also supplies voltage to all the remaining lamps at the proper PWM voltage to achieve the requested intensity. The PRNDL incorporates LED lamps that are illuminated at full intensity with the ignition in the ON position. When the park lamps are active, the IPC will adjust the PRNDL LED intensity as requested by the IPM by varying the pulse width modulation of the LED dimming signal circuit to the lamps. All interior back lighting lamps are permanently grounded.