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Home >> Mercury >> 2008 >> Milan Base, 3.0 1, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 721 (Exterior Lighting System) >> Diagnostic Tests >> Headlamps >> Pinpoint Tests >> Pinpoint Test E: The Headlamps Are On Continuously >> Normal Operation

Normal Operation

WARNING: This page is about a different car, the 2007 Lincoln Mark LT and 2007 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.

When the headlamp switch is placed in the HEADLAMPS ON position, voltage is routed through circuit 15 (RD/YE) to the multifunction switch. The vehicle security module (VSM) also supplies voltage to circuit 15 (RD/YE) when the autolamp system has requested the exterior lamps on.

For low beam headlamps, the multifunction switch routes voltage through circuit 13 (RD/BK) to the central junction box (CJB) fuses 23 (10A) (RH headlamp) and 25 (10A) (LH headlamp). After passing through the fuses, voltage is then carried through circuits 161 (DG/OG) (RH headlamp) and 160 (DB/WH) (LH headlamp) to the low beam headlamps. If equipped with daytime running lamps (DRL), the DRL resistor also routes voltage to circuit 13 (RD/BK) (at a reduced voltage) when the ignition is in the RUN position and the high beams are off.

For high beam headlamps, the multifunction switch routes voltage to circuit 275 (YE) to the high beam relay. When the high beam relay receives battery voltage from circuit 275 (YE), the high beam relay is energized. Battery voltage received from the CJB is then routed to circuit 12 (LG/BK) via CJB fuse 35 (20A). Voltage is then carried to the high beam headlamps through circuit 12 (LG/BK). The fog lamp relay coil uses the high beam circuit as a ground when energized.

Possible Causes

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