electrical and ignition Horn Talk

[7502]

I have a new to me '75 2002. Among other things, my horn doesn't work. I only have one horn that I could find which I removed and tested to work out of the car. The Hayne's manual shows I should have two horns if the wiring diagram is correct. This got me thinking, providing I can get it working, should I have two horns and if so are they tuned to different pitches or frequencies such as on my 1963 Karnmann Ghia. Using two horns of different pitches produces the best beep in my book. I have removed and cleaned the contacts on all three relays on the drivers side of the engine bay. Does this sound like a problem with the steering wheel contacts? 

[Simeon]

I think early cars came with two horns, tuned as 'high' and 'low' but this was rationalised to a single horn on later cars. 

 

The the horn is directly powered from the battery without a fuse and switched via one of the relays above the battery. 

 

Check for for voltage at the horn terminal and work your way back to the relay. Does the relay operate when you press the horn push? My horn uses one of the old style cylindrical can relays and I have found that when left sitting for a while it can stick open. A sharp rap with a screwdriver handle usually helps. 

[Conserv]

I agree with Simeon that later cars moved to a single horn, perhaps around 1975, unless it happened with the square taillights (1974).  And, yes, the wiring diagrams seemed to show two horns until the end of '02 production.  So....does un-used wiring exist for the second horn on these later cars?  I'd love to know but I guess I've been too lazy -- at least for the last 40 years -- to investigate this issue myself.

 

Regards,

 

Steve

 

[7502]

Horn still non functioning. There's no traces of old wiring from a second horn so it appears it never was set up for a second horn. I have traced the power wire from the horn to the most forward of the three 4 prong relays on the left side of the engine bay. From there it joins the the large wrapped wire bundle and to its' fuse that leads to the firewall and then up under the dash.  So far I have confirmed the horn works and it it has  a good ground I've also cleaned all four contacts under the horn buttons.  I've tried to swap out the different 4 prong relays but no go. I wonder if my steering wheel is properly grounded?  I wish I had a better wiring diagram.

 

Could someone tel me what circuits are controlled by the three different 4 pron relays? All my on-line sources have yet to contain that basic information. Thanks.

[halboyles]

Check to make sure there is a ground wire around the steering coupler, could be a braided wire or just a thin single wire around two of the bolts.  That is the ground for the horn.  Just search for "steering coupler" on the forum and you will find many references to the ground wire.  Sorry I couldn't immediately find a good pic.

 

[Simeon]

The relays are horn, high beam headlights, low beam headlights. 

 

Check out http://www.2002tii.org/kb/246

[7502]

Thanks Simeon, have not seen that site before. Looking at the wiring diagram parts list it indicates that the right horn was an option. I guess the original owner didn't want to spend the extra bread for a second horn. When I get the horn functioning it might be time to dig out some of my old VW 12 volt horns and make it a duel horn system. And halboyles, thanks for the tip on the ground connector to the steering coupler that sounds like a promising solution. The previous owner left that area a little disturbed to say the least. Also, my car came with a bulky console for a dealer installed Behr AC unit which I removed last weekend freeing up easier access under the dash so it will make solving this wiring issue easier. Only down side is I need to come up with something to mount the hazard light switch and a radio of some kind. Its fun to make progress. 

[Guy Cocquyt]

There should be a brass contact ring just below the steering wheel on the column, and the steering wheel should have a spring loaded contact which is in contact with the ring. If this is missing or not properly contacting, no horn.

Sent from my SM-T110 using Tapatalk

[Simeon]

Now you have the wiring diagrams and wiring colours, trace put the wiring at the relay and see if you can get it to operate by false feeding it's coil 12V and applying a ground to the other terminal.  If that works and the horn sounds then you can rule out the high current side and concentrate on the relay activation side. 

 

Most at likely the horn contact or the continuity wire / braid as has been pointed out. 

[MildSeven]

I have a '76, not sure if it's original but I have 2 horns.

 

i think you're already on the right track.. but just in case.

if you ground the brass ring, around the steering column, the horn will sound. I'd work my way backward from there.

['76mintgrün'02]

My 76 only had one horn, but I replaced it with a pair I took out of a 320i; along with the steering wheel, which needed to have a contact spring added, since the 'button' is on the wheel in the 2002 and on the 'stalk' on the e21. It can be seen on the wheel in these photos.  If you do not put a little grease on the ring, it will make a very annoying screeching sound... I've found.  Anyway, this photo shows the brass ring which Guy mentioned above.

 

 

[7502]

I removed the upper and lower steering wheel covers and can see the brass ring section just loose around the steering wheel shaft. The yellow/brown wire connection is good and tight, and the spring loaded contact on the wheel is good.  Is that ring held on by anything, or is it just tight when the top and bottom covers are screwed together?  Now when I turn on the ignition,  the horn sounds, so I have gone from no horn to all horn.  I had to disconnect the horn for the time being. 

 

On the plus side today I installed a new 320i alternator and it works perfectly, fixed the right side view mirror, fixed the rear side lights so I'm not letting the horn problem get me down but I would like to figure it out. 

 

Edit : I should have mentioned that the inner diameter of the brass contact ring is metal and it shorts out on the shaft. Shouldn't the shaft part of the ring be insulated from the contact ring?

Edited September 4, 2016 by 7502

[JohnH]

My experience with horns would suggest that 99.99% of all horn problems are with the wiring connector at the horn, plus its the easiest one to look at first! .

[7502]

JohnH, done that right away.

 

Eric

[Buckeye]

4 hours ago, 7502 said:

I removed the upper and lower steering wheel covers and can see the brass ring section just loose around the steering wheel shaft.  Is that ring held on by anything, or is it just tight when the top and bottom covers are screwed together?  

 

yes, If you look at that ring closely you will see a section of it's parameter not round (clocking wise at 6 o'clock). That flat section needs to be seated in the lower steering wheel cover. you will notice lower steering cover has notch in to receive that ring. Share a picture with us when that is seated properly for reference.