Pinpoint Test A: The Control Illumination Is Inoperative: Expedition

When the headlamp switch is in the park or headlamp ON position, a voltage signal is sent to the instrument panel dimmer switch on circuit 14 (BN). The instrument panel dimmer switch generates a variable pulse width modulated (PWM) voltage which is distributed to the instrument cluster and the instrument panel switches on circuit 19 (LB/RD). The instrument panel dimmer switch is grounded through circuit 57 (BK).