Instrument Cluster Description and Operation: Tachometer

The instrument panel cluster (IPC) displays the engine speed as determined by the body control module (BCM) via a class 2 message. The engine control module (ECM) determines the engine speed and sends a controlled area network (CAN) serial data message to the BCM indicating the engine speed. The tachometer will default to 0 RPM if:

• The ECM detects a malfunction in the engine speed sensor circuit.
• The BCM detects a loss of CAN communications with the ECM.
• The IPC detects a loss of class 2 communications with the BCM.