P0654 Infiniti Engine Speed Output Circuit
– Instrument Cluster harness is open or shorted
– Instrument Cluster circuit poor electrical connection
– Faulty PCM
The Instrument Panel Cluster (IPC) supplies a voltage to the Engine Speed Output circuit. The Powertrain Control Module (PCM) creates the Engine Speed Output signal by rapidly grounding this circuit via an internal switch called a driver. The other components on this circuit recognize the voltage being pulled to ground as an indication of engine speed. The driver supplies the ground for the component being controlled. Each driver has a fault line which the PCM monitors. When the PCM commands a component ON, the voltage of the control circuit should be low (near 0 volts). When the PCM commands the control circuit to a component OFF, the voltage potential of the circuit should be high (near battery voltage).