Normal Operation

WARNING: This page is about a different car, the 2010 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

The lighting control module (LCM) sends voltage signals to the headlamp switch through circuits 220 (VT/OG), 1400 (TN/WH), 1032 (WH/BK) and 1033 (RD/YE). The headlamp switch routes a signal to ground through circuit 57 (BK) for any given headlamp switch position. If the LCM detects a fault with any of the headlamp switch inputs, the LCM defaults the exterior lamps on.

When the LCM detects the headlamp switch in the HEADLAMPS ON position and the multifunction switch in the LOW BEAM position, the LCM provides voltage through circuits 160 (DB/WH) and 161 (DG/OG) to the LH and RH low beam headlamps.

When the LCM detects the headlamp switch in the HEADLAMPS ON position and the multifunction switch in the HIGH BEAM position, the LCM provides voltage through circuits 1337 (VT/YE) and 1335 (YE/WH) to the LH and RH high beam headlamps.

The LCM sends a reference signal to the multifunction switch through circuit 12 (LG/BK). When the multifunction switch is placed in HIGH BEAM the position, the voltage signal is routed to ground. When the multifunction switch is placed in the FLASH-TO-PASS position, battery voltage is routed to the LCM. When the SJB detects a request for the flash-to-pass or high beam headlamps, the LCM provides voltage to the high beam headlamps.

DTC B1472 (Lamp Headlamp Input Circuit Short to Ground) - sets when the LCM detects a short to ground on the headlamps on input circuit.
DTC B1570 (Lamp Headlamp High-Beam Circuit Short to Ground) - sets when the LCM detects a short to ground on the high beam request input circuit.

This pinpoint test is intended to diagnose the following:

Wiring, terminals or connectors
Headlamp switch
Multifunction switch
Windshield wiper motor
LCM