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Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53310
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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My horn is not working. fuses good. getting power to fuses.

Can you tell me where... Show More
Can you tell me where is the horn relay located on a 1997 E320
Submitted: 8 years ago.
Category: Mercedes
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replied 8 years ago.
Hi, the horn relay on your Mercedes is incorporated into the K40 relay module located under a cover in the right rear corner of the engine compartment. the module has a row of fuses on top of it. Fuse #6 is for the horn. Check that first.
Customer reply replied 8 years ago.
Do you have a diagram or skematic. I'm not sure what thwe K40 module looks like, but I pull the big fuse marked 40 in the number 6 spot and it was good.
Marty, Mercedes Technician replied 8 years ago.
It sounds like you've found the K40 relay. There should be five 15 amp fuses and that big 40 amp fuse on top of the module. The horn fuse is one of the blue 15 amp fuses. I'd check all of them. I'll see about getting you a schematic if you need one but I'm sure I can walk you through the diagnosis.
Customer reply replied 8 years ago.

Okay lets check it out again.


Customer reply replied 8 years ago.
No all those fuses are good replaced each one including the 40amp. Still no horn. What should I try now? Vehicle will not pass inspection without the horn.
Marty, Mercedes Technician replied 8 years ago.
The next thing to do is to see if you are getting power from the ignition switch and ground from the horn button to the K40 relay. On the K40 relay there are 5 plug connectors. The connector in position D should be a 2 wire connector. Unplug the connector and put your voltmeter across the 2 terminals in the connector. With the key on have someone press the horn button. You should read battery voltage across the plug.
Customer reply replied 8 years ago.
I am out of state now. Will be out for 2 weeks. I will ressume my troubleshooting when I return. Thanks for the help. Stay tuned.
Marty, Mercedes Technician replied 8 years ago.
Ok William, I'll be here when you get back.