How to Replace the Relay in Your Car

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How to Replace the Relay in Your Car

When activated, car relays act as electromagnetic switches that send electricity moving in certain directions. Most car switch relays harness small surges of electricity to trigger large surges of power that emanate from larger relays. Auto relays inevitably wear down and require replacement. Car owners should learn the reasons why relays malfunction, as well as how to replace relays in their vehicles.


Why Relays Need Replacement

Frequent use is the number one reason why relays fail to function properly. Drivers activate relays thousands of times and the constant switching on and off causes wear and tear to the circuitry. Relays also succumb to operating in wildly vacillating weather conditions, from steamy summer heat to the cold of the dead of winter. Engine heat can also prompt a relay to activate, without any impetus from the owner of the car. Electrical circuits that turn on and off independently of the driver can overload the system and start an electrical fire.


Consult Your Owner's Manual

The designs of electrical systems vary amongst cars, trucks, vans and SUVs. Although vehicle owners can isolate relay problems by using a multimeter, a more accurate way to target the faulty relay is referring to the vehicle's owner's manual. Owner's manuals typically include detailed diagrams of the vehicle's electrical system, including the battery and relays. Once you isolate the faulty relay, you can then perform basic maintenance, such as examining the connector for grime or corrosion. A brief wiping down of the contacts may rejuvenate a faulty relay. Since an overheated engine can cause relays to activate, you should check the coolant level to ensure proper engine temperature.


Choose a Replacement Relay with Identical Amp and Volt Ratings

Once you find the faulty relay, make sure to replace the faulty relay with a relay that possesses the same amp and voltage ratings. Replacing a relay with a relay that produces different amp and voltage levels can cause serious damage to the vehicle. Manufacturers design most vehicles to include relays of similar amp and voltage levels, but check to ensure you purchase a relay that has matching ratings and pin connectors to replace the faulty relay.


Replacing the Relay

Prevent electricity from flowing by disconnecting the car, truck, van, or SUV battery cables. You then remove the screw that secures the relay and release the connector tabs. Use a pair of pliers to hold the relay firmly as you disconnect the relay from the connector. Avoid pulling the wires during the removal of the relay. Apply a small amount of dielectric grease at the connection points of the new relay. Dielectric grease prevents corrosion from forming by repelling moisture. Connect the new relay to the connector tabs and screw the relay securely into position. Examine the wiring before reconnecting the battery cables.

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