lzzhang

My RX350 horn stops working after driving for a while. Every morning, the horn works. However, after driving for a while, the horn stops working. It is the same on the next day. What could be the problem and how I can test to find out the problem?

Thanks

salimshah

Debug procedure is to check for voltage at the horn connector [voltmeter can at times deceive you and mechanics use a lamp as load]. But if you get no voltage then you trace back to the steering handle.

Was any work done which triggered the problem?

Working horn is required to drive on the public streets, so I would move it up in the priority list.

Salim

m1964

Had this problem when my 2012 was still under warranty.
The dealer started from checking the clock spring inside steering wheel but it turned out that one of the wires from one horn to another was not soldered properly. The horns are connected in parallel. If yours is under warranty go to your dealer.
If not, I'd go to either good electrician/mechanic shop or to a good alarm/stereo shop. The horns are easily accessible after grill removal.

iolmaster

iTrader: (1)

This is not definitive, but it sounds like the spiral cable (clock spring) in the steering wheel. I have had to do this repair on other Lexus cars. My SC430 was doing the very same thing and it was the spiral cable.

m1964

As I explained in my earlier post, it was not the case with my RX, but they started from there.
Very difficult to diagnose intermittent electrical problems.
I'd bet my 5p the problem is under the hood.

E46CT

Any prior accidents or repairs? Start with a good visual inspection. Sounds like heat may be a factor. After you've been driving, is there a drastic change? Like are you in a garage before your commute, do you turn the heater up, is it freezing outside, etc.

if you are heating the cabin, i could see a clock spring.

also when the horn DOESNT work again, try turning the steering wheel. maybe hold down the horn as you turn the wheel and see if it blips on. if so, it's your clock spring. if not, likely a wiring issue somewhere.