To replace a faulty turn signal relay, turn off the engine, disconnect the battery, open the hood of the vehicle, locate the relay, remove the faulty relay, and replace the old relay with a new relay that is identical to the damaged version. Turn the engine on, and test the installation. Read the vehicle service manual before starting the installation.
Stop the engine, turn off the ignition, open the hood, secure the hood with a hood support rod, and unplug the battery, disconnecting the negative cable first. Purchase a replacement relay from an auto parts store according to the manufacturer's recommendations. To find the relay, first locate the fuse box, normally located around the wheel, between the door and dash, or under the dash. If necessary, pry off the cover under the steering column to gain access to the relay.
Depending on the model and make of the vehicle, carefully pull out the relay from its housing, or twist it counterclockwise to release it. Insert the replacement relay in the fuse panel or electrical connector. Reconnect the battery cables as appropriate, turn on the ignition, and start the vehicle. Activate the turn signals to test the replacement. If the relay doesn't work, change the signal bulbs or check the wiring.