1qwiksearchindex Quick Search

Headlight relay how to

Back .....................................................Home...........................................Horn relay

The same basic principles apply to the headlight circuit as the horn circuit, however the headlights consume a significant amount of amperage for extended periods of time.

As always, determine that all wiring system components such as clean and tight ground connections, bulb type and sockets, plugs etc. are all in proper order. Study the task at hand, and fully comprehend electrical procedures. All wiring modifications must be performed in a professional manner to avoid a possible catastrophe!!

Headlight switches contain a pair of circuit breakers that automatically trip off intermittently if excessive resistance is present in either the head or tail light circuit. Incidentally, the use of halogen type bulbs consume considerably more energy than a typical sealed beam unit .This additional load can often tax the light switch beyond its limits until the circuit breaker can no longer handle the resistance.

The most effective means of reducing the load on the system is by adding two relays (or a double relay), one relay for each of the headlight beam .

Mounting of relays should be near front of the vehicle, preferably close to the "feed"wires on the left front inner fender panel. I recommend using at least 30 amp relays. Incorporating a 20 amp fuse or fusible link in line with the battery feed wire of at least 10 gauge should give adequate protection. Connect to battery positive at the starter solenoid.

Most relays come with instructions and relay terminals are marked for ease of installation. Remember, electrical gremlins prey on the ignorant !!

Locate the two headlight feed wires running from the dimmer switch (a wiring diagram costs only $5.00 at Shasta Mustang Supply) . Splice the high-beam feed wire to one relay switch terminal, and the low-beam feed to the second relay. The next step is to connect each corresponding wire out to the lights to the accessories terminal of the relay. Connect ground wires and the conversion is complete.

Dim or flickering lights and overheating light switch will be a thing from the past.

Pretty simple, eh ?