Instrument Panel Cluster (IPC) Description and Operation: Tachometer

The instrument panel cluster (IPC) displays the engine speed as determined by the powertrain control module (PCM)/engine control module (ECM). The IPC receives a GMLAN message from the body control module (BCM) indicating the engine speed. The tachometer will default to 0 RPM if:

• The PCM detects a malfunction in the engine speed sensor circuit.
• The BCM detects a loss of GMLAN communications with the PCM/ECM.
• The IPC detects a loss of GMLAN communications with the BCM.