Tachometer: Description and Operation

TACHOMETER

The instrument panel cluster (IPC) displays the engine speed as determined by the powertrain control module (PCM) or the engine control module (ECM). The IPC receives a GMLAN message from the body control module (BCM) indicating the engine speed. The tachometer will default to 0 RPM if:
- The PCM/ECM detects a malfunction in the engine speed sensor circuit.
- The IPC detects a loss of GMLAN communications with the BCM.