Where is the horn relay on a 2011 Lexus is250?

The horn relay on a 2011 Lexus IS250 is normally located in the engine compartment fuse/relay box, with a diagram on the lid that marks the HORN position. If it isn’t found there, you may also find a HORN relay (or horn-related fuse) in the interior fuse box beneath the driver’s side dash.

Engine compartment fuse/relay box

To locate and inspect the horn relay in the engine bay, follow these steps:

• Open the hood and locate the large black fuse/relay box in the engine compartment. It is typically near the front of the engine bay, often toward the passenger side or near the strut tower.


• Check the diagram on the inside of the lid for a relay labeled “HORN” or “HORN RELAY.”


• Carefully pull the relay straight out to inspect it or replace it with a known-good relay of the same type and pin configuration.


• Also check the adjacent fuse labeled “HORN” or the horn circuit fuse to ensure the circuit is intact.


• Reinsert the relay and securely close the cover before testing the horn.

If you find no HORN relay in the engine bay box, or the lid diagram doesn’t match, consult the owner’s manual or a service manual for your exact VIN, as some configurations use the interior fuse box for the horn circuit.

Interior fuse box as backup

Some IS250 configurations place the horn relay (or the horn fuse) in the interior fuse box under the driver's knee panel. Before reaching for tools, verify the diagram on the inside of the interior fuse box cover.

• Open the driver’s side footwell panel and remove the interior fuse box cover.


• Locate the relay labeled “HORN” or the slot designated for the horn circuit; pull it carefully for inspection or replacement.


• If the relay is missing or seems faulty, replace it with a compatible unit and reassemble the cover.

After testing both locations, re-check the horn to see if it functions. If it still doesn’t work, there may be issues with wiring, the horn itself, or the steering-wheel switch that require further diagnostic work.

What to do if the horn still doesn’t work

Safety first: disconnect the battery before handling electrical components to avoid shorts. Test the horn button and wiring by briefly applying power directly to the horn unit to confirm it works, then verify whether the relay trips when you press the horn button. If the relay clicks but the horn doesn’t sound, inspect the horn wiring and the horn unit itself. If the relay does not click at all, try replacing the relay or the fuse as a next step.

Summary

The horn relay on a 2011 Lexus IS250 is usually found in the engine compartment fuse/relay box, with the lid diagram identifying the HORN position. If not located there, the interior fuse box under the driver’s dash may house the horn relay or fuse. By locating the correct box, inspecting the HORN label, and testing with a known-good relay, you can diagnose most horn relay issues. If problems persist, seek professional service to check wiring, the horn, and related control circuits.

Where is horn relay located?

The horn relay is typically located inside the vehicle's main fuse box, most often under the hood. To find its exact location, check the fuse box lid or your car's owner's manual for a diagram that identifies the horn relay, which is often labeled with an "R" and a number. Some newer vehicles may not have a separate relay, with the horn function integrated into the body control module (BCM). 
This video shows the location of the horn fuse and relay in a Ford Edge: 59sQuiteAlrightYouTube · Feb 29, 2024
How to find and identify the horn relay

1. Locate the fuse box: Check under the hood for the main fuse box, which is a common location. Some vehicles have secondary fuse boxes in other locations, like inside the cabin, which you should also check if the main one doesn't contain the relay. 
2. Consult the diagram: Open the fuse box and look for a diagram on the inside of the lid or consult your owner's manual. This diagram will show the layout of fuses and relays. 
3. Identify the horn relay: Find the symbol for the horn relay on the diagram. It is often labeled with an "R" followed by a number (e.g., R40). 
4. Check other possibilities: If you can't find a separate horn relay, its function may be integrated into the BCM in some models, particularly some newer GMC Sierras. 

Troubleshooting the horn relay

• Swap the relay: If you find a relay with the same part number, you can swap it with the horn relay as a test. If the horn starts working, the original relay was faulty. 
• Check for common symptoms: A faulty relay can cause the horn to be weak, silent, or sound constantly. 
• Use a multimeter: You can use a multimeter to test the relay's coil resistance. 
• Inspect wiring: Also check the wiring connections to the horn itself for any signs of corrosion or looseness. 

How to tell if a horn relay is bad?

Symptoms of a bad horn relay include a horn that doesn't work at all, a clicking noise without a sound, or a weak or inconsistent sound. Other potential signs are the horn honking uncontrollably, a burning smell, or other electrical issues related to the steering wheel such as a malfunctioning airbag or cruise control, which could indicate a related clock spring problem. 
Common symptoms

• No sound: The horn does not function at all when the button is pressed. 
• Clicking noise: You hear a clicking sound from the relay's location in the fuse box but the horn itself does not sound. 
• Weak or inconsistent sound: The horn makes a faint or intermittent sound instead of a strong, continuous tone. 
• Constant honking: The horn activates on its own and will not turn off. 
• Burning smell: A burning odor may come from the fuse box area, indicating a burnt-out relay. 

Related symptoms (may indicate a different issue)

• Airbag light is on: This can be a sign of a faulty clock spring, which is a component in the steering column that also connects the horn. 
• Other steering wheel controls not working: If the horn, radio, or cruise control buttons fail simultaneously, it points to a clock spring issue. 

What are the common problems with a 2011 Lexus IS 250?

Common problems for the 2011 Lexus IS 250 include the engine's tendency for carbon buildup, which can cause check engine lights and misfires, as well as electrical issues like malfunctioning window switches and GPS problems. Other potential issues include transmission problems, particularly a tendency for the computer to fail, and a lack of power and fuel efficiency.
 
This video explains the carbon buildup issues in the Lexus IS250 and how to fix them: 1mBern on CarsYouTube · Mar 24, 2025
Engine and performance

• Carbon Buildup: Due to its direct injection system, the engine is prone to carbon buildup on the valves, which can cause misfires and a rough idle. 
• Transmission: Some models experience issues with the transmission control computer (PCM) failing, leading to problems like rough shifting and illuminated check engine lights. 
• Performance: The IS 250 is not known for strong acceleration and has lower fuel efficiency compared to some competitors. 

This video demonstrates how to fix transmission shifting problems in the Lexus IS250: 55sJack FletcherYouTube · Feb 11, 2024
Electrical and technology

• Electrical Gremlins: Owners have reported a range of electrical problems, including non-functional window switches and memory seats, as well as other intermittent issues. 
• GPS and Infotainment: Software issues with the GPS, radio, and other user interface functions have been reported, sometimes requiring a software update or the use of adapters for better functionality. 
• Interior degradation: Plastic interior components, such as dashboard trim and side moldings, can degrade, crack, or fray over time. 

This video talks about the electrical issues and problems with the infotainment system in the Lexus IS250: 1mNavs GarageYouTube · Aug 13, 2022
Other potential issues

• Lack of rear-seat space: The rear seats do not fold down, limiting the vehicle's cargo capacity. 
• Fuel efficiency: The fuel economy is not a strong point for the IS 250. 
• Steering: Some drivers find the steering to be uncommunicative, and body roll can be noticeable, which may be disappointing for performance enthusiasts. 

This video explains the 5 things you need to know about the Lexus IS250 and IS350: 58sLife with SondurenYouTube · Apr 9, 2023

What year Lexus is 250 to stay away from?

You should generally stay away from the 2007-2009 Lexus IS250 models, as they are known to have engine issues with carbon buildup and problems with the dashboard and door panels melting or becoming sticky. While later models (2010+) addressed some of these issues with engine revisions, the 2007 and 2008 model years seem to have the most reported problems and are considered the ones to avoid. 
Years to avoid

• 2007-2009: These model years had known issues with carbon buildup in the engine, which was revised in 2010. They are also associated with sticky or melting dashboard and door panels. 

What to look for instead

• 2010 and newer: Lexus revised the engine in these later models to address the carbon buildup issue, making them more reliable. 
• IS350: If your budget allows, the IS350 is a more powerful and reliable option, though it is more expensive to buy and operate.