Tachometer: Description and Operation

TACHOMETER

The instrument panel cluster (IPC) displays the engine speed as determined by the engine control module (ECM)/powertrain control module (PCM) via a class 2 message. The tachometer will default to 0 RPM if:
- The ECM/PCM detects a malfunction in the engine speed sensor circuit.
- The IPC detects a loss of class 2 communications with the ECM/PCM.