Circuit Description

The tachometer is directly controlled by the PCM using a Pulse Width Modulated (PWM) signal, based on information received from the Crankshaft Position (CKP) sensor. With ignition on, PCM receives battery voltage from the instrument panel cluster circuit (IPC circuit No. 121) and senses if the circuit contains a fault by using a diagnostic feedback signal. The PCM provides the ground to the tach signal directly.

DTC will set if there is an open, short to ground or short to voltage in the tachometer circuit. Tachometer diagnostic feedback signal is continuously checked when ignition is on. The tachometer is not controllable by the scan tool.