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1978 DeVille - horn switch

Started by Koa, May 07, 2021, 04:59:27 AM

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Koa

Hi Caddy-guys,
my horn doesn t function since the purchase. Now I finally decided to to work on it. I removed the steering wheel and it seem like there is some part missing.
The white plastic ring - is it complete or is a part broken and lost?
When I connect one of the three contacts to the ground, the horn runs.
Can You please check the photos and give me some advice?
77 Coupe DeVille 425 ci - federal, red+ white interior
78 Fleetwood Brougham 425 ci - California, white + red int.
98 DeVille with the famous Northstar engine
32 Tatra 57  -  do You know that?

TJ Hopland

I was going to say in a 77/78 I believe the issue is usually in the horn pad itself but looks like someone already dealt with that part and changed it to a 79+ wheel.   I have a 80's wheel on my 73 and I don't recall having any issues with the horn but that was 73 to 8x.   Maybe there is something different about the 77/78?

Whats the history on this?    It was working?   Or it never worked and you are not investigating and it was disconnected?
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

V63


V63

#3
The white piece is attached with 3 screws from the back and the plastic  'Connection' tower goes thru a hole to the front. There is a large spring I do not see that is in between that completes the ground. You are missing the large spring and that is one reason why it won't work .

The 77-8 horn pad VINYL  covering would 'shrink' with age just enough to activate the horn. Our new 77 did that one cold evening in the garage, car was maybe 5 years old with extremely low Garage kept miles. The horn was on so long it fried the relay. I made the horn only 'active' whilst driving the car, and a bypass switch  to manage the problem.

The later pads (1979 up) were not as vulnerable to the problem with that design effectively lasting over a decade.

Eric DeVirgilis CLC# 8621

The dash woodgrain and wheel are 1979 - are you sure the car is a 1978? No matter.

If you're able to get the horn to sound, I suspect the ground wire was disconnected because it was staying on all the time as a result of decomposition of the foam membrane between the backing & contact plates resulting in closing the circuit at all times. What needs to be done is to drill out the rivets holding the pad together and CAREFULLY remove the old foam membrane so that it can be used as a template to cut out a new foam piece. Sandwich back the way it was and rivet the assembly back together and reinstall.



A Cadillac Motorcar is a Possession for which there is no Acceptable Substitute

Koa

Quote from: V63 on May 07, 2021, 01:08:49 PM
The white piece is attached with 3 screws from the back and the plastic  'Connection' tower goes thru a hole to the front. There is a large spring I do not see that is in between that completes the ground. You are missing the large spring and that is one reason why it won't work .

The 77-8 horn pad VINYL  covering would 'shrink' with age just enough to activate the horn. Our new 77 did that one cold evening in the garage, car was maybe 5 years old with extremely low Garage kept miles. The horn was on so long it fried the relay. I made the horn only 'active' whilst driving the car, and a bypass switch  to manage the problem.

The later pads (1979 up) were not as vulnerable to the problem with that design effectively lasting over a decade.

Do You please have a picture of the spring?

And how about the plastic t)ring - does anyone know, if it compete?
77 Coupe DeVille 425 ci - federal, red+ white interior
78 Fleetwood Brougham 425 ci - California, white + red int.
98 DeVille with the famous Northstar engine
32 Tatra 57  -  do You know that?

81 BENY Biarritz

Hi Koa,  Here is a picture of the back of my 81 wheel.   Looks to be the same.   The spring is used to make contact with the end of the small wire from the horn pad to conduct power down to the three copper terminals inside the steering column on a Telescopic steering column.   To me it looks like your plastic ring is intact.   You just need the spring.   Please note that the spring is slightly conical in shape that doesn't seem to show very well in this picture.  It also has the one end with a short bend in it to sit at the bottom of the plastic tube where the spring twist lock horn wire connector fits to make electrical contact.  You can see it if you zoom in on the brass coloured terminal on the bottom edge of the white disk.   My suspicion is that a previous owner removed it to prevent the horn from sounding randomly due to deterioration of the foam piece that separates the horn base from the electrical contact pad under the horn vinyl covering.   It apparently is a very common problem as this style of horn pad ages.   Hope it helps.   Dave

Cadillac Fleetwood

If you need this spring, send me a PM.

Charles Fares
Forty-Five Years of Continuous Cadillac Ownership
1970 Fleetwood Brougham
1969 DeVille Convertible
1989 Fleetwood

"The splendor of the most special occasion is rivaled only by the pleasure of journeying there in a Cadillac"

Koa

Quote from: 81 BENY Biarritz on May 13, 2021, 04:15:05 PM
Hi Koa,  Here is a picture of the back of my 81 wheel.   Looks to be the same.   The spring is used to make contact with the end of the small wire from the horn pad to conduct power down to the three copper terminals inside the steering column on a Telescopic steering column.   To me it looks like your plastic ring is intact.   You just need the spring.   Please note that the spring is slightly conical in shape that doesn't seem to show very well in this picture.  It also has the one end with a short bend in it to sit at the bottom of the plastic tube where the spring twist lock horn wire connector fits to make electrical contact.  You can see it if you zoom in on the brass coloured terminal on the bottom edge of the white disk.   My suspicion is that a previous owner removed it to prevent the horn from sounding randomly due to deterioration of the foam piece that separates the horn base from the electrical contact pad under the horn vinyl covering.   It apparently is a very common problem as this style of horn pad ages.   Hope it helps.   Dave

Tahnx for the info. It seems to be the same on my car. But except this spring I miss a part, that sits in the column, positioning this spring to center, cause otherwise the spring would slide to one side and would not touch the 3 brass pins.
77 Coupe DeVille 425 ci - federal, red+ white interior
78 Fleetwood Brougham 425 ci - California, white + red int.
98 DeVille with the famous Northstar engine
32 Tatra 57  -  do You know that?

81 BENY Biarritz

Koa,  if you look carefully at your last picture of the inside of your steering column you can see the small plastic tabs on the inside edges of each of the three copper contacts.   The diameter of the spring at that end is just sufficient to go outside these tabs.   As the spring is under compression it will make contact with the three copper contacts and not slip off of these retainers.   If you get the correct spring you should just be able to reassemble as is.   
Have you checked whether you have continuity between the horn wire and the metal backing of the horn pad yet with a multimeter?  If you do it is like pushing on the horn pad and your horn will sound all the time.  I have not had an issue with mine but I have read that when the horn pad sees a high temperature (like sitting in the sun in the summertime) sometimes it  will expand enough to compress the deteriorated foam separation pad and the horn will go off without warning.   Here is a picture from another post of what it looks like inside (basically).  You might want to figure out where the horn relay is on the relay panel under the dash in advance so you can pull it out if you have an unexpected issue of the horn sounding off in the future.  Hope this helps, Dave

Koa

Thanx a lot.
Now I understand, what probably happened to my car in the past. In summer the plastic just bent and made the horn to to run all time. The previous owner "repaired" that by simply throwing the spring away.
Now I was even wondering why he did it, while checking the pad/switch I just realized, it would be OK - but I did not check it IN THE SUMMER HEAT.

This is why I simply adore this forum - without experiences like this I (and others happy Caddy owners too for sure) could just give it up.  :-))
77 Coupe DeVille 425 ci - federal, red+ white interior
78 Fleetwood Brougham 425 ci - California, white + red int.
98 DeVille with the famous Northstar engine
32 Tatra 57  -  do You know that?

Koa

By the way, do You think, the wheel is the same 1979 through 1992?
77 Coupe DeVille 425 ci - federal, red+ white interior
78 Fleetwood Brougham 425 ci - California, white + red int.
98 DeVille with the famous Northstar engine
32 Tatra 57  -  do You know that?

TJ Hopland

#12
77-78 was the wide horizontal bar and the one that was really prone to the horn pad warping issue.   79 to when air bags became standard on all models was the frown sort of design.  There were slight variations in the colors and if they were leather wrapped but I believe the overall basic wheel was the same.   

Your photos and Dave's photo in reply #6 are the 79+ style.    Daves photo in #9 is the 77-78 style.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason