Instrument Panel Cluster (IPC) Description and Operation: Tachometer
WARNING: This page is about a different car, the 2004 Pontiac Sunfire and 2004 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
The IPC displays the engine speed as determined by the BCM via a class 2 message. The BCM receives a class 2 message from the PCM indicating the engine speed. The tachometer will default to 0 RPM if:
- The PCM detects a malfunction in the engine speed sensor circuit.
- The IPC detects a loss of class 2 communications with the BCM.
- The BCM detects a loss of class 2 communications with the PCM.