Speedometer

A Vehicle Speed Sensor (VSS) signal is supplied by the Powertrain Control Module (PCM) via discrete inputs to the IPC. The VSS discrete signal is pulled up to ignition voltage in the IPC. This vehicle speed pulse train is expressed as 4000 pulses per mile. The IPC uses the VSS data received from the PCM and a software program to determine the proper vehicle speed to display. The ENG/MET button is used in order to change the displayed vehicle speed between English and metric units.

Any calculated speed above 155 MPH or 260 km/h is ignored and the last valid speed is displayed. The vehicle speed is normally displayed on the speedometer gauge. The IPC also has a VF digital speed display that is normally OFF. The DSPL MODE button is used to change the display. Pressing the button once adds the digital speed display to the IPC with the speedometer gauge. Pressing the button a second time turns OFF the speedometer gauge, so that the vehicle speed is only being displayed on the digital speed display. A third press of the DSPL MODE button will return the speed display to the normal setting.