19998 Ls400 Horn Problems

[Walser]

I recently had a problem with the horn not working when you depress it while driving, on my '98 LS400. I checked the fuse in the engine compartment and that was fine. I wanted to check and see if the horns were the problem, so I depressed the "panic" button on my ignition key and the horn alarm sounded so the horns are not the problem ? I then tried depressing the horn inside, and it now works ?

I wanted to see if this happens again, does anyone have any advice as to what the issue is ?

I know there is a (1) horn relay in the fuse box panel as well, and (2) there is a mechanism in the steering wheel that activates the horn when you are driving. Has anyone had this problem, or have any idea what could cause this ?

Regards,

Alan

[landar]

It appears to have been your horn "button" in the steering wheel and not the relay since the horn worked with the panic button. Contacts in buttons are notorious for becoming oxidized over time and intermittent without constant use. The horn button typically gets so little use (at least in my case) that simply depressing the button multiple times 'wipes' the contacts and cleans them up somewhat. Could explain why it now works.

[1990LS400]

The horn in my similar 2000 LS400 stopped working last summer. I rarely use my horns and discovered they had quit working only when my own wife damned near backed her Camry into my LS in a nearby shopping center parking lot. (It's a long story. Don't ask.)

The problem was the horn/airbag pad. The pad would not depress properly and it was obvious that something like a spring inside the pad was broken or weak. It my case the problem was on the right side of the horn pad which makes sense I guess since I am right handed and use my right thumb to honk the horn. The horn worked intermittently for a few days and then stopped working entirely.

The indie repair shop I use replaced the horn pad/airbag assembly with a used one. I think the total cost was around $750 - certainly not much more than that. A new horn pad/airbag assembly was something like $2,000+. I was told that the horn pad could not be disassembled and repaired. I have the old one out in the garage - had planned to tear it apart to see how it is constructed but never bothered.

[olex400]

My LS 400 97' has the same problem. I took out the relay and short-cutted the two pins and the horn blew. I also opened the relay, put it on and forced the contacts: same result, so I assume both the horn and the relay work properly. Which brings me to the question if there is any way to reach the horn pad contacts under the cover. The springs work well and you can hear it hitting the contacts when pushed.

[1990LS400]

From what I've seen on Lexus forums, a more common cause of a non-functioning horn on an LS400 is a defective "clock spring". The issues I had seems to have been unusual. My knowledge of clock springs is limited to what I've read and seen in silly videos like ...

I see used clock springs on eBay pretty cheap ... $50 or so. I assume there is a diagnostic method of telling which part is bad - horn pad, clock spring, etc.

Attached is a rear view of the old horn pad / air bag assembly from my 2000 LS400 - your probably looks similar. I assume the connectors on the back of it connect to the clock spring assembly.

[olex400]

Thanks for the information. How do I take the horn pad off, is it held by clips?

[steve2006]

Before doing anything regarding the Horn Pad make sure you disconnect the battery and then wait at least 20 minutes for any back up circuits to discharge as the airbag system is also in the Horn Pad.

Failure to do so may cause unexpected operation of the airbag!.

To remove the pad prize out the 2 plastic covers on the side of the steering wheel then slacken of the 2 star/torx screws ( one each side) as can be seen in the picture below, just slacken them fully they do not fully come out.

Disconnect the airbag connections and this is what you should see.

The connector at the top is normally attached to the clock spring and it is the top right connection ( single black wire) which is the horn feed to the push bars, the black wire should be rivoted to the right side push bar.

The horn circuit is completed by pushing either spring loaded bar down thereby earthing the relay coil via the steering colunm and sounding the horn.

[landar]

When a clock spring is bad, you may also get an airbag warning light on the dash. Have you seen any indications other than the horn not working?

[Walser]

Thanks to everyone for all of the reply's and comments.

Unfortunately, my horn continues to work intermittently ! While I can depress the "panic button" on the ignition key the horn and everything works perfectly, which is why I think the problem has to be in the horn pad or clock spring ? Maybe the dealer or indie can remove the horn pad and check the contacts, etc !

To Randall's previous comment, I do not have an air bag warning light that is coming on.

[olex400]

Thanks for all the comments and help.

There are no other malfunctions, no warning lights, cruise and the phone controls work fine. It's just the horn not blowing. My guess is that there is a brake in the cable from the clock spring to the fuse box (relay).

Tomorrow afternoon I will take it all apart following Steve's instructions. On the left side of the steering wheel is the phone controls panel I think it can be taken off to find the exact screw as described.

I will post the results here.

[steve2006]

If you pm me your Email I will send you the factory manual section for the disassembly and testing of the horn circuit.