PCM Controlled Tachometer Diagnosis

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

CIRCUIT DESCRIPTION
The tachometer signal is a Pulse Width Modulated (PWM) signal. The Instrument Panel Cluster (IPC) supplies ignition voltage to the tachometer control circuit through a pull-up resistor. The low side driver in the PCM grounds the tachometer control circuit in relation to engine speed.