Instrument Cluster Description and Operation: Tachometer
WARNING: This page is about a different car, the 2011 Cadillac DTS. 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 engine control module (ECM). The IPC receives a serial data message from the ECM indicating the engine speed. The tachometer will default to 0 rpm if:
- The ECM detects a malfunction in the engine speed sensor circuit.
- The IPC detects a loss of serial data communications with the ECM.