Instrument Cluster Description and Operation: Tachometer
WARNING: This page is about a different car, the 2010 Pontiac G5 and 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
The instrument panel cluster (IPC) displays the engine speed as determined by the PCM/ECM. The IPC receives a serial data 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 BCM detects a loss of serial data communications with the PCM/ECM.
- The IPC detects a loss of serial data communications with the BCM.