My horn on my 2006 es 330 lexus wont work what

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Remove seat track plastic covers. Remove seat bolts

Your dealer checked it? Lots of these newer cars have systems on their radios to prevent them from working when the battery is disconnected. Sort of a device to deter theft if unit is not going to work. Thing is that the dealer has a code that is entered to reset the radio and get it to work after the battery is re connected. Surprised the dealer did not check for this.

May be in security mode, you may need computer reset. Not sure, just a guess.

usually in pairs two of one type threaded into exhaust before catylitic converter and two of another type threaded into exhaust behind catylitic converter(looks like little muffler in exhaust close to engine.)

dead battery? bad ground wire off battery or pos. side?

IT was the switch in the glovebox. Didn't even know there was one there, but it is and it will lock out the dash trunk switch if not properly set. It was probably bumped when they changed out the interior air filter.

there is a cancel button in the glove box, check this first to make sure its not activated.

no there is not really a downside dealers are good it doesn't really matter who does it but lexus is more familiar with lexus vehicles than toyota because they specialize in it but something like that is simple .