Interior Lamps Dimming

CIRCUIT OPERATION
The dimming of all instrument Panel incandescent lights and vacuum fluorescent displays is based on the value of the driver-adjustable dimming control on the Headlight Switch. The dimming of the vacuum fluorescent displays and the incandescent back lighting is only possible when the Park Lights are on.

Incandescent Dimming
Whenever the Park Lights are on, voltage from I/P Fuse #42 is applied to the Headlight Switch at connector C2 terminal "C." This signals the Headlight Switch's PWM Module to generate a pulse width modulated signal based on the position of the dimmer control. The Headlight Switch connector C1 terminal "D" and connector C2 terminal "B" applies the pulse width modulated signal to the incandescent lamps and the instrument Cluster's dimming input connector C1 terminal "A2." The bulbs with this signal applied will dim or brighten depending on the frequency of the signal generated.

Vacuum Fluorescent Dimming
Whenever the Park Lights are off, no voltage is applied to the Park Lights on input terminals on the Instrument Cluster (connector C1 terminal "A1") and Radio Control Head (connector C2 terminal "A"). This signals the cluster and Radio vacuum fluorescent displays to be at full brightness. When the Park Lights are on, voltage is applied to the Cluster's and Radio's Park Lights on input terminals signaling them to respond to the dimming control in the Headlight Switch.

Dimming of the vacuum fluorescent displays are controlled by the Instrument Cluster based on the pulse width modulated signal applied by the Headlight Switch to the Cluster's dimming input connector C1 terminal "A2." In response to the dimming input signal the I/P Cluster generates a pulse width modulated signal at connector C1 terminal "A4" to dim the Radio Control Head. This pulse width modulated signal is sent through CKT 724 to the Radio Control Head connector C1 terminal "C." As the on time (duty cycle) of this signal increases the vacuum fluorescent display of the Radio Control Head gets dimmer.