There are many things that might prevent your Jetta’s horn from working properly. Pinpointing the problem is usually a very easy task and fixing it is free more than 50% of the time. Even when there is a problem, repair typically only requires the right parts and hand tools. Find out what’s going on with your Jetta’s horn.
Step 1: Check the Fuse
This is the first place to look. Locate your fuse box and fuse for the horn. Most times, it’s pretty obvious when a fuse is broken, but if damage isn’t visible to the eye, you should still check it with a multimeter to be sure. If the fuse is blown, replace it and test the horn again. This is also a good time to check the wire running from the fuse panel to horn relay — make sure the wire isn’t damaged. Should this not fix the problem, keep moving to the second step.
Step 2: Check for Horn Function
Open the hood of your Jetta and have someone press the horn inside the car. Locate the horn itself and listen for any sounds coming from the horn that you might not be able to hear with the hood shut. Also, put your hand on the horn to feel for vibrations when the horn is pressed by your assistant. If you hear sounds, locate the adjustment screw on the horn and adjust it with a screwdriver. Should this not be the problem, keep on troubleshooting.
Step 3: Test the Connection
For this step, connect a jumper wire to a good ground on your Jetta. Have a helper press the horn while you make contact with the horn using the other end of the jumper wire. If the horn starts to work at this point, fix the ground connection so the horn makes good contact with the chassis.
Step 4: Check the Voltage
Have someone press the horn while you’re checking voltage with a voltmeter. If voltage is reaching the horn, but it is not functioning, it will need to be replaced. However, if no voltage is reaching it, continue on to the next step.
Step 5: Check the Wiring
Now its time to check the wire running from the horn to the relay for continuity. If there is an open, fix it and retest. Keep going to the next step if the wire does not have an open.
Step 6: Checking the Horn’s Relay
Test the relay for voltage at the power-and-control circuit with a voltmeter while someone else pushes the horn. If the relay doesn’t have voltage, replace it and retest.
In these steps, you should have found your problem. If not, carefully review them to see if you may have missed something. Should the horn continue to not sound off after checking this components, it may be time to consult an expert VW mechanic for further diagnostic help.