Instrument Cluster Description and Operation: Tachometer

The IPC displays the engine speed as determined by the ECM. The IPC receives a GMLAN message from the ECM indicating the engine speed. The IPC receives the engine speed information from the BCM via a GMLAN serial data message. 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 GMLAN communications with the ECM.
• The IPC detects a loss of GMLAN communications with the BCM.