Instrument Cluster 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). The IPC receives a serial data message from the engine control module (ECM)/powertrain control module (PCM) indicating the engine speed. The IPC receives engine speed information from the body control module (BCM) via serial data messages. The tachometer will default to 0 RPM if:

• The ECM/PCM detects a malfunction in the engine speed signal circuit.
• The IPC detects a loss of serial data communication with the ECM/PCM.
• The IPC detects a loss of serial data communication with the BCM.