Special Equipment Option
DIGITAL SPEEDOMETER MODULEThe Special Equipment Option (SEO) instrument cluster uses a digital speedometer module in addition to the gauges and indicators of the standard instrument cluster. The digital speedometer module receives ignition voltage, ground, and a Vehicle Speed Sensor (VSS) signal independent of the instrument cluster connector.
ODOMETER
The odometer display of the digital speedometer module can be switched from ODO to TRIP by the ODO/TRIP Switch on the Accessory switch. The ODO/TRIP switch closes circuit 717 to ground when switched to TRIP.
TRIP ODOMETER
The trip odometer can be reset to zero by the trip reset switch. The trip reset switch is a momentary switch that provides ground potential to circuit 376 for the digital speedometer module.
ENGLISH/METRIC
The digital speedometer module can be selected to display English (MPH) or metric (km/h) by removal or installation of the english/metric fuse (FUSE 25). Installation of FUSE 25 will ground circuit 811 and select the metric mode of the display. Removal of FUSE 25 will select the english mode of the display.
SEO VF ILLUMINATION
When the digital speedometer module will turn on all segments of the Vacuum Fluorescent (VF) displays during engine start-up for a display check. The VF displays of the digital speedometer and the radio can be step dimmed to a night mode by the VF dim displays signals from the headlamp switch (circuit 308) when it is in PARK or HDLP positions. When the park lamps are ON, the VF display can be adjusted with the I/P dimmer switch through circuit 230. When the SEO display switch is in the ON position the display works normally. When the SEO display switch is in the OFF position and the HDLP switch is in the OFF position, the VF display and the DRL lights are off even if the engine is running. This happens because the display switch is sending a signal through circuits 328, the SEO switch panel diode, and circuit 308 to the digital speedometer module which represents a signal showing that the HDLP switch is in the PARK or HDLP position. This signal would cause the display to go to the step dim mode. The module then looks at the VF dim signal to determine the brightness. Because the headlamp switch is in the OFF position the I/P dimmer switch is not supplying any voltage to circuit 230. Therefor the module sees the I/P dimmer switch as in the OFF position and turns the display OFF. The SEO switch panel diode serves to prevent backfeeding from circuit 308 to circuit 39 if the display switch and the headlamp switch are both on with the ignition off.