Horn Diagnosis and Replacement Guide for the 1971 BMW 1802
If your classic BMW's horn has gone silent, this guide will help you troubleshoot the issue and find the right part.
- Always test the fuse and horn relay before assuming the horn unit has failed; these are common and simple fixes.
- Horn failure is often due to corroded electrical connections or a bad ground because of its location behind the grille.
- An aftermarket horn from a brand like Standard Ignition is a cost-effective and reliable replacement for the original part.
- Replacement is a simple DIY job that requires basic hand tools and should take less than an hour.
Is Your Horn Really Broken? Check the Basics First.
On a classic car like the 1971 BMW 1802, a non-working horn is often caused by a simple electrical problem, not the horn unit itself. Because the horn is located at the front of the car, its electrical connections are prone to corrosion from rain and road grime. Before you decide to replace the horn, a few quick checks can save you time and money.
Start with the Simple Stuff
- Check the Fuse: This is the easiest first step. A blown fuse is a common culprit.
- Listen for the Relay: Have a friend press the horn button while you listen for a 'click' sound from the relay, which is typically located in the engine bay near the brake fluid reservoir. If you hear a click, the relay and horn button are likely working, and the problem is probably the horn or its wiring.
- Test the Horn Directly: If you can safely access the horn, you can test it by running jumper wires directly from the battery to the horn's terminals. If it honks, the horn is good, and the problem is in the wiring, relay, or ground connection. If it stays silent, the horn itself has failed.
Choosing an Aftermarket Horn: Quality and Fit
Finding a new original equipment (OEM) horn for a 1971 vehicle can be difficult and expensive. Aftermarket parts are a practical and popular choice. For a classic BMW, you want a part that fits correctly and provides a reliable sound.
Standard Ignition (SMP): Standard is a well-known aftermarket brand that has been around for a long time. Their parts are generally considered a solid, cost-effective replacement for the original, offering a good balance of quality and price. A Standard Ignition horn should provide a direct fit, making installation straightforward.
A Note on Sound
Some basic aftermarket horns may have a different tone than the original Bosch or Hella units your BMW came with. Some owners describe the sound as more "tinny." Your 1802 may have originally come with a dual-horn setup (one high tone, one low tone). If you are replacing only one, be aware the sound may not match the remaining original horn.
Cost of a New Aftermarket Horn (1971 BMW 1802)
| Part Type | Price Range |
|---|---|
| New Aftermarket (Standard Ignition) | $54.41 |
| Used OEM | $25 - $75 |
| Shop Labor | $60 - $120 |
Frequently Asked Questions (FAQ)
Where is the horn located on a 1971 BMW 1802?
The horn is almost always located behind the front kidney grilles, mounted on the car's front support panel. This location exposes it to weather, which is a common reason for failure.
Is replacing the horn a difficult job?
No, this is a very easy job for a DIY mechanic. It usually involves removing the front grilles for access, unplugging the electrical connector, and removing a single mounting bolt. Always disconnect the battery before working on any electrical components.
My horn just makes a weak, muffled sound. What's wrong?
A weak or "sick cow" sound is usually caused by low voltage from a poor electrical connection, internal corrosion, or a failing diaphragm inside the horn. Sometimes, cleaning the electrical contacts can fix it. Some original horns have an adjustment screw on the back that can sometimes be turned to restore the proper sound.
If my horn doesn't work, is the horn itself always the problem?
No. In fact, on a classic car, the problem is just as likely to be something else in the circuit. The most common failure points are a blown fuse, a bad horn relay, corroded wiring and ground connections, or the horn button contacts in the steering wheel. It's important to test the circuit before buying a new part.
Technical Specifications
OEM Part Numbers: 61331367312 61331367356
Voltage: 12V, Connection: 2-Terminal
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.