Tachometer

The instrument cluster receives a discrete tachometer signal from the powertrain control module (PCM). The instrument cluster calculates the engine RPM based on the signal. The instrument cluster then drives the tachometer gauge to a corresponding level in response to the signal. The instrument cluster performs the following functions:
^ Ensures that the tachometer gauge is at the red line before the fuel cutoff
^ Determines if the tachometer is toggling The instrument cluster sends a message to the body control module (BCM) through the SPI serial data message for diagnostics.