Clarifications with removing airbag

[Shdwdrgn]

2004 TB, I have a dead horn button and need to remove the airbag to check if there's any damage to the switch. (Already swapped relay, checks fuse, confirmed horn works from keyfob)

So I *think* if I disconnect the battery for 10-20 minutes, that will discharge the airbag so it doesn't go off in my face? I don't know if I actually need to unplug it to work on the horn, but I figure just my luck something would happen to pull the wires loose, so why take chances? But if I do want to disconnect the airbag, am I right that the 10-20 minute discharge also allows me to unplug the two wires? Is there anything else I should know?

As far as the horn button goes, I've seen threads about either the top contacts or the circular copper ring getting damaged, so I'll do what I can to inspect those. Also seen threads about the grease getting hard over time and preventing contact. And while I have it apart I'll throw a voltmeter across the contacts just to make sure the wiring is even working up to that point. I think that should cover it?

 

[TollKeeper]

Before doing all that, try holding your horn down while turning steering wheel full lock left and then full lock right.

I hate messing with air bags too!

 

[Shdwdrgn]

Hmm interesting idea, I'll give that a shot. Leaving work shortly so I can test it before I head home.

 

[Mooseman]

Also check the wiring schematics and see which wire is the horn. Try grounding that wire from the bottom of the steering column. Should be a blk/yel wire. Check that the wire is getting ground from the BCM with the fob.

 

[Shdwdrgn]

Yep, already checked the fob, working fine there. Unfortunately I'm not as young as I used to be, hanging upside down under the sheering column isn't something I can easily do any more so I figured I'd check the top-side stuff first.

Regarding holding the horn button while turning the wheel fully in both directions... not even a peep. One thing I forgot to mention though, the reason I originally suspected the horn button is because of the way it slowly failed. At first just missing sometimes when I tapped it, building up to where I had to directly push on it rather than a quick tap, until it got to the point where it would only sounded very periodically.

It's been completely dead for about three years now but a couple weeks ago a kid was screwing around on his bike in the middle of the street and then decided to just suddenly dive in front of me. Luckily I was watching him but I would have felt a lot better if I could have scared the hell out of him from hitting my horn right behind him so he would remember to look around before he ends up learning it the hard way.

 

[Mooseman]

The button itself is a very simple thing. I would suspect more the clockspring. I've taken the airbag off before. Just remove and unplug. Just make sure you grounded yourself to be sure you don't have any static in your body.

 

[Shdwdrgn]

Grounded myself to the truck frame or to an Earth ground? And I assume I still have to disconnect the battery so the airbag can discharge?

 

[mrrsm]

@MAY03LT did a nice Step By Step of these procedures on YouTube:

 

[Mathoran]

At 2:15 in that Video the white connector with the 2 red wires. If its broken and doesnt stay locked in the horn wont work either. I believe I was able to get just that part when mine went bad.

 

[Mooseman]

And this is the one for disabling the airbag (basically disconnect the battery and wait about 10 minutes)

 

[budwich]

The button itself is a very simple thing. I would suspect more the clockspring.

The thing with "pointing at the clockspring" is that there are many connections going thru that and likely that if one is gone others would also have some issue... but as suggested, it can be checked. The problem with the horn button contact is two fold. One the plastic retainer can dislodge or break resulting in no physical contact of the subtending copper surfaces. The other issue is grease and / or corrosion. Some form of grease (dielectric?) is used. If its dielectric, then it is expecting enough pressure on the contact surface to "micro displacement / breakdown" to allow contact for electric flow. So if the spring is deformed or otherwise, then nothing happens electrically. A meter will be your friend once you get to the area. The other thing is wiring at the horn "rim". I seem to recall that there is a ground wire there. That wire can be broken such that there is no grounding to "send" thru the contact to the bcm.

 

[TollKeeper]

The thing with "pointing at the clockspring" is that there are many connections going thru that and likely that if one is gone others would also have some issue... but as suggested, it can be checked. The problem with the horn button contact is two fold. One the plastic retainer can dislodge or break resulting in no physical contact of the subtending copper surfaces. The other issue is grease and / or corrosion. Some form of grease (dielectric?) is used. If its dielectric, then it is expecting enough pressure on the contact surface to "micro displacement / breakdown" to allow contact for electric flow. So if the spring is deformed or otherwise, then nothing happens electrically. A meter will be your friend once you get to the area. The other thing is wiring at the horn "rim". I seem to recall that there is a ground wire there. That wire can be broken such that there is no grounding to "send" thru the contact to the bcm.

While that is true, and I dont know if @Shdwdrgn has it, but if he doesnt have steering wheel controls, or a DIC, or if he has steering wheel controls but has a aftermarket radio, the only things that can really go bad is the horn, and airbag (I think).

 

[Shdwdrgn]

As a matter of fact I do have steering wheel controls + DIC, and all of that is working fine (although I think three out of four of the backlights have died), so it sounds like the ground wire issue shouldn't be a concern here, along with the possibility of the whole cable being sheared.

I'm hoping to have some time to pull this apart over the weekend so I can at least see if there's any obvious parts that I need to find replacements for. I figure it's likely I'll have to pull it apart at least a couple times, maybe I can see about converting those lights to LED while I'm in there.

 

[Shdwdrgn]

Pulled the airbag today and didn't immediately see any problem until I started poking around. The red wire practically fell out, and one pin of the spring-loaded clip is broken off. Yep, that'll do it! I just ordered a new contact module and I'll also clean up the contacts while I have everything apart.

I was really hoping pulling the battery would finally make the CD light stop blinking on my stereo. It's been blinking since I replaced the battery last year. It's one of the Bose 6-disc units, would be nice if it actually worked but I know there are no discs in the player. Maybe after I finish the horn work I'll see if I can get it to accept a CD, then eject it and hope that finally resets the indicator? (That or it won't give the disc back, I've had that happen before.)

 

[Mooseman]

Or a piece of black tape will cure it

 

[Shdwdrgn]

Huzzah! I have a horn again. And that took way longer than needed.

So I wish someone had mentioned... the horn contacts have an up and down direction! And naturally, I put them in the wrong way, so when I snapped the airbag back in place it was offset up about 1/2" and the holes for getting to the release pins couldn't be reached. What a royal pain to get it back out again! Just in case anyone else does this to themselves -- I was able to get a screwdriver between the airbag and the shroud that goes around the steering wheel column so I had enough room to shine a flashlight in there and try to figure out what I could work with. I have a long 2.5mm hex wrench that was the right size for poking the pin when I initially took the airbag off, and I was able to fit the angled side back down through the gap in the shroud and work it into the slot for the release pin on both sides. I found it easier once the hex wrench was in place to use some pliers on the end of the wrench so I could get enough pressure to push the release pins in far enough. It took awhile, but I finally got both pins released and then swapped the horn contacts around so everything was in the right position.

I also used some 1000-grit black sandpaper to lightly clean the copper contacts. I was surprised at the resistance reading between the contacts, about 500K ohms on the clean surfaces, but the horn worked fine when pushing on all four corners of the airbag. Also of note, I never did need to remove the wires from the airbag, but still better safe than sorry. Also make sure you touch a ground point on the truck body before touching the airbag, there's always a small chance of a static charge setting it off.

Whew, so yet another thing off my checklist! We have cold weather coming in this week so I may just leave other items for next year, but I have two issues with the radio... First off the CD player mechanism seems to be jammed so the CD light constantly blinks. I did manage to get it to reset after plugging the battery back in, but it came back on while I was out getting gas (I heard the motors moving and then it beeped and the light started flashing again.

The second issue has been a problem since I got the truck. First off if I hit a bump, there's a loose wire and the noise filter stops working, so I get engine noise in the front left channel. I tried pulling the panel on the passenger side once (down by the floor) but didn't find anything obviously loose there, but maybe there's a common ground to the dash and door speaker on each side? Another issue is that it is absolutely terrible at picking up radio stations, even though I'm only about 30 miles from Denver. It seems especially worse in the Winter where sometimes just going over a hill causes a lost signal. I did grab an aftermarket antenna and plugged that into the radio, tried putting it up on the dash or holding it out the window, but it was no better than the body antenna. So I've got no ideas about that issue. Good news is I picked up another radio years ago to test the antenna issue (it was still bad for the 30 seconds before it locked out), so I might just try swapping the circuit board between radios to fix the CD problem (I don't know anyone who can reset the code for me).

Ah well, I need to take care of other things before Winter sets in so I probably won't have time to pull the dash apart again. It's just something to thing about until I do have time to start poking at things again.