Circuit/System Description

The engine control module (ECM) creates the vehicle speed output signal by pulsing the vehicle speed signal circuit to ground at a rate of 4KPPM. The ECM monitors the voltage at the vehicle speed output signal circuit to determine when the voltage is out of the normal operating range. The instrument panel cluster (IPC) receives vehicle speed data from the ECM via the serial data circuit for display in the speedometer. The radio, object detection module and the inside rearview mirror (ISRVM) receive vehicle speed data via a discreet vehicle speed signal circuit from the ECM. The radio, object detection module and the ISRVM use the 4KPPM vehicle speed signal from the ECM to determine vehicle speed.