Standard Ignition DS-300 Headlight Dimmer Switch

Headlight Dimmer Switch for Ford and Mercury

Standard Ignition DS-300 is a headlight dimmer switch built for column-mounted lighting control on a wide range of Ford, Lincoln, and Mercury vehicles. It uses copper alloy conductors for strong electrical conductivity and is 100% tested for mechanical and electrical switching performance.

• Part number DS-300 headlight dimmer switch
• Combination switch function with turn signal control included
• Latching high beam operator and momentary high beam flasher included
• 12-volt electrical design with 2 female connectors
• Blade terminals, 12 terminal quantity, bolt-on attachment
• Complete assembly with aluminum and plastic finish
• New replacement part from Standard Ignition

Detailed Product Overview

This Standard Ignition DS-300 headlight dimmer switch is designed for vehicles that use a steering-column-mounted dimmer and turn signal switch. It serves as the control point for switching between low and high beams, while also handling turn signal operation in the same assembly. The robust housing and tested switching performance make it a practical replacement for worn or intermittent column switch assemblies on Ford Ranger, Ford Mustang, Ford LTD, Mercury Cougar, and related applications.

This part cross-references Standard Ignition DS115 and DS123 for the same application.

What This Switch Helps Fix

• High beams that will not latch on
• Dimmer switch failure causing no low-beam or high-beam changeover
• Intermittent headlight operation from worn internal contacts
• Turn signal control issues tied to the combination switch assembly
• Electrical resistance from aging switch conductors

Installation Notes and Fitment

Install as a bolt-on replacement using the existing column-mounted switch location and connector layout. Verify the vehicle uses the correct configuration before installation, especially for models noted without flash-to-pass or without auto headlight dimmer. Compatible With 1987-1989 Ford Aerostar, 1984-1989 Ford Bronco II with floor shift, 1986-1989 Ford Ranger with floor shift, 1985 Ford Ranger with floor shift, 1983-1984 Ford LTD without flash to pass, 1983-1984 Ford Ranger, 1984 Lincoln Mark VII without auto headlight dimmer, 1981-1984 Lincoln Town Car without auto headlight dimmer, 1980-1984 Mercury Capri without flash to pass, 1984 Mercury Grand Marquis without flash to pass, 1980-1981 Mercury Grand Marquis without flash to pass, 1983 Ford Escort without flash to pass; dimmer and turn signal switch, 1981-1983 Ford Fairmont without flash to pass, 1981-1983 Ford Mustang without flash to pass, 1981-1983 Ford Thunderbird without flash to pass, 1980-1983 Lincoln Mark VI without auto headlight dimmer, 1980-1983 Mercury Zephyr without flash to pass, 1978-1982 Ford LTD, 1980-1982 Mercury Cougar without flash to pass, 1980-1981 Mercury Marquis without flash to pass, 1978-1980 Ford Fairmont with headlight dimmer switch located on the steering column, 1978-1980 Ford Fairmont, 1979-1980 Ford LTD with headlight dimmer switch located on the steering column, 1979-1980 Ford Mustang with headlight dimmer switch located on the steering column, 1979-1980 Ford Mustang, 1978-1980 Ford Pinto, 1980 Ford Thunderbird with column mounted switch, 1978-1980 Ford Thunderbird, 1980 Lincoln Continental, 1980 Lincoln Continental without auto headlight dimmer, 1980 Mercury Monarch without flash to pass, 1979 Mercury Capri, 1979 Mercury Cougar, 1979 Mercury Grand Marquis, 1979 Mercury Marquis, and 1978-1979 Mercury Zephyr.

Quality Assurance

Standard Ignition builds this switch with copper alloy conductors and durable aluminum and plastic materials, then tests each unit for both mechanical action and electrical switching performance. That combination supports consistent operation in daily-service use on Ford, Lincoln, and Mercury column-switch applications.