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Headlight Relay Switch Problems

by Andrea Stein

Headlight relays switches refer to electrical components that interrupt a current between conductors via an electromagnet to control headlight activation, deactivation and brightness. Headlight relay switches can suffer problems for a number of reasons, but can often be detected and resolved.

Bad Connection

A headlight relay switch may malfunction due to a loose or faulty electrical connection to the coil, which generates a magnetic field when voltage is applied. The driver should check the wire connection and tighten it if loose, or replace it if corroded or otherwise damaged.

Bad Coil

Excessive current conditions can cause the solenoid coil to burn out, often resulting in loss of headlight function. The driver should replace the headlight relay switch to restore proper headlight operation.

Bad Switch

The switches used in the headlight relay operate via one circuit to control the parking lights, another current for driving lights and the third operates the high beams. One or multiple switches in the set can fail due to corrosion, excess current or exposure to damp conditions, resulting in total loss of headlight function or the inability to switch between beam brightness. The operator should inspect the switches for signs of damage or wear and replace them as needed.

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