I have a 99 E300TD. The horn quit. As far as we (Phil and I) can tell is that it is powered by a relay. I placed a 12 volt test light between the two leads at the horn. I have a full glow on the light. This is the strange part. The test light glows when I press the horn, when I do not press the horn, and it lights both when the key is ON or OFF? The relay does make the tell tail click when the horn is pressed at the wheel. Phil said to replace the relay first, ($18.00 investment with shipping) before spending money at an electrician. I agree and bought the relay.

Any one have any idea about this one!

Thanks,

Scott

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1999 E300 DT 178k
1960 Ford Thunderbird Convertible 82k
2000 BMW R1200 CE 12k
2000 Nissan Xterra SE 145k
1994 Go Ped 1,000,000 miles