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 displays the engine speed based on a GMLAN message from the body control module (BCM) indicating the engine speed. Refer to Data Link Communications Description and Operation and Body Control System Description and Operation. 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.