Failure analysis: Intermittent horn

[Tomioka]

01 Tundra didn't pass it's yearly safety check due to inop horn which now means solving an electrical issue since this is now a critical fix. I've checked the most basic stuff until I did some googling that similar Tundra owners had with the column shaft tilt assy bearings. The horn button completes the ground circuit from the chassis, through the bearings, horn button, then to the horn relay. Wiggling the steering wheel while holding the horn completes the ground as the rusty bearings try to ground to chassis so that confirms the issue.

I opted to replace the whole assembly instead of cleaning the old grease and repacking it with new grease. The failure seems to be a lack of grease in the bearings from the factory and bearings open to the elements. The new assembly also lacked grease. In this case I encased the new bearings with white lithium grease to prevent open exposure to rusting.
I also replaced the column shifter assembly with the updated version since they are prone to breaking.

 

[Donald]

Portable freon boat horn in a can?

 

[JMJNet]

For the horn, not sure if you checked the fuse?
I had experience with a good old fuse that cause intermittent issue with the horn.
I replaced it and it was good to go, not sure why.

 

[Tomioka]

Originally Posted By: Donald
Portable freon boat horn in a can?


If safety checks weren't mandatory lol. I don't use the horn a lot so I didn't find out until the mechanic told me the horn wasn't working.

Picture of the new assembly. Insufficient amount of grease in the bearings possibly leading to repeat failure. Forgot to add to original post.

 

[Tomioka]

Originally Posted By: JMJNet
For the horn, not sure if you checked the fuse?
I had experience with a good old fuse that cause intermittent issue with the horn.
I replaced it and it was good to go, not sure why.


Yep checked the fuse and related connections with a DMM. I almost chalked it up to a broken wire in the engine bay but I remember coming across a similar issue with another vehicle and I checked the horn pad/button. Further googling came out to be poor ground connections through the bearings.

 

[andyd]

May I be so rude as to inquire the price of the assembly? I would have tried to drive out the bearing, clean it, and repack it with wheel bearing grease. If not, I would have cleaned and repacked it in place.This bearing doesn't have very much stress on it.

 

[Tomioka]

Originally Posted By: andyd
May I be so rude as to inquire the price of the assembly? I would have tried to drive out the bearing, clean it, and repack it with wheel bearing grease. If not, I would have cleaned and repacked it in place.This bearing doesn't have very much stress on it.


I paid $80.01 but price varies with the dealership. Toyodiy.com shows it at $63.62.

 

[Wolf359]

Originally Posted By: Kibitoshin

If safety checks weren't mandatory lol. I don't use the horn a lot so I didn't find out until the mechanic told me the horn wasn't working.


I'm not sure I can go anywhere without using the horn at least once. Lots of crazy drivers here that don't pay attention. Sometimes you really have to lean on it too otherwise they would just crash into you when they switch lanes without checking their blind side. I cringe all the time when I see drivers backing up just using their rear view mirror, they'll get a nice view just before they hit someone.

 

[Chris142]

I think packing it with grease will cause no contact and no horn.

 

[CT8]

You fixed it right the first time Good job! I quit Micky Mousing things about 40 years ago.

 

[Carmudgeon]

I had a different failure mode in an old Mazda beater.

Intermittently, the horn would sound on its own in the middle of the night.

"Who's that idiot blowing their horn and disturbing the peace?"

Oops, that idiot was me.

The horn pad/switch was a sandwich of two sheets of copper fingers separated by a layer of foam.

Over time, the foam disintegrates, and you can guess what comes next.