Tachometer: Description and Operation

TACHOMETER

The instrument panel cluster (IPC) displays the engine speed as determined by the powertrain control module (PCM)/engine control module (ECM). The IPC receives a class 2 message from the ECM/PCM 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 PCM/ECM.