Instrument Cluster Description and Operation: Tachometer

The IPC displays the engine speed as determined by the ECM. The IPC receives a serial data message from the ECM indicating the engine speed. The ECM transmits the engine speed to the body control module (BCM) via the serial data circuit. The BCM then transmits the engine speed to the IPC via the serial data circuit. The tachometer defaults 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 BCM.
• The BCM detects a loss of serial data communications with the ECM.