Repairing a horn on a Volkswagen Jetta depends largely on where the problem lies. The 2001 Jetta has two horns, both mounted in the left front fender well, just behind the bumper. The problem can lie in the horns themselves or in the wiring or relay for the horns. Inspect the relay and wiring first to determine what needs fixing. It can always help to consult with a wiring specialist if that is where the problem lies.
Open the fuse/relay box under the car's dashboard and connect an ohmmeter to the terminals labeled 85 and 86 on the horn's relay to measure resistance, then remove the relay and connect the ohmmeter to terminals 30 and 87. Replace the relay if it fails any of the tests indicated in the Tips.
Disconnect the electrical connectors for both horns and connect a voltmeter to the voltage supply terminal. Have another person press the horn in the car with the voltmeter connected. If there is no voltage, disconnect and replace the relay's wire.
Connect the ohmmeter to the wiring connector's brown wire and a metal ground. If the resistance measures 5 ohms or more, check and repair any problems (a loose wire, for example) in the ground circuit.
Remove the mounting bolts for the horn and remove it if you have confirmed that the relay and wiring are all in good condition.
Install the replacement horn with its mounting bolts and reconnect the electrical connector.
