– Instrument Cluster harness is open or shorted
– Instrument Cluster poor electrical connection
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 ofspeed. 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 voltage).