Tachometer

The tachometer displays the engine speed in RPMs. The engine RPM is taken from the Powertrain Control Module (PCM) via the class 2 serial data line. The instrument cluster compares the engine RPM data with a 16 point look-up table in order to determine needle deflection. A smooth filter ensures a continuous response. The instrument cluster drives the tachometer gauge to 0 RPM if the following conditions occur:
^ The engine RPM data is lost.
^ The PCM is in a state of health fault.