: Mystery Horn



Timothy60
03-14-06, 10:10 PM
Hello,
It's easy to take a horn for granted until there is a problem. When I press on the padded center section of the steering wheel in my 1993 Fleetwood, the following may happen: A. The horn blasts normally or B. there is a 3-4 second delay before the horn sounds or C. the horn does not sound at all. There seems to be no logical pattern why this happens; it's completely unpredictable and . . . unsafe. I've replaced the relay with one from NAPA and I've cleaned the wire connections on the 4 horns. Nothing has helped. Any suggestions on what I can do to get the horn working properly again?
Thank you,
Tim
1993 Cadillac Fleetwood 151,878 miles and still running swift and strong
Syracuse, NY

Junkman
03-16-06, 10:56 PM
I would be inclined to believe that the problem is corrosion in the horn contacts in the steering wheel. You will need to disassemble the top portion of the steering wheel to get at them. If the car is equipped with a air bag system, I would leave this service to a person that is experience with the handling of this component. The reason for the delay is that even though a contact is made, there is enough resistance that it is insufficient to complete the circuit. After a few seconds, the resistance is overcome and the current then is sufficient to make the contacts to the relay and the horns will blow. It isn't a common problem, but one that I have experianced in the past.

Timothy60
03-17-06, 06:58 AM
Thanks, Junkman! Your diagnosis makes a lot of sense in explaining the delay of the horn. I'd like to take the air bag part of the steering wheel off to fix it because it sounds easy to do, but I'll take your advice and skip it. I'll have a mechanic who knows how to disarm the airbag system take a look at it. Wouldn't want that to deploy unexpectedly! What a mess. :mad:

Timothy60
04-30-06, 09:07 PM
How about this complication: The horn blows 100% of the time when the ignition is OFF. When the car is running, it is totally unpredictable if it will blow or not. Why? Someone who really knows auto electrics might know the answer to this one. As for me, I'm stumped, and I've asked many people who cannot give an answer. How about it?

Junkman
04-30-06, 09:28 PM
I still believe that this is a ground problem. I would start with the negative ground cable where it is attached to the front frame rail. Remove the bolt, and clean the area under the cable and also the cable end itself. Then look for any copper ground straps that might connect the engine or the body to the frame. I am not that familiar with cars of the late 1970 and beyond as to how they grounded each component. In the 1950's & 60's they used copper grounding straps from many parts of the car to each other and to the frame. The only reason that I am aware of the ground strap to frame attachment on the Fleetwoods is because I own a 1978 Commercial Chassis Cadillac and was also experiencing similar grounding problems. On my car, the ground strap is run to the bolt that holds the alternator, so the block is grounded. This left the chassis with a poor ground. I resolved that by adding an additional ground strap from the engine to the chassis. I would also check all the lighting to see if there are any that are not as bright as the others. This will also indicate a poor ground. The horns themselves are grounded to the front radiator core support. You can clean and reattach these also to see if it might help. If there is a poor path to ground, the first item to use that path will usually have the best ground and the second item will suffer. In your case, this is the horns.
While we are on the subject of horns, has anyone ever seen a trumpet horn on a 1977 or later Cadillac. On the Cadillac information page for 1978 (http://100megsfree4.com/cadillac/cad1970/cad78d.htm), it indicates that it was an available option, however I have yet to find it listed in the parts book. The only thing that I find listed is the A & C notes as optional and the D & F notes as standard. If anyone has a A and or a C note horn from a 1976 or later Cadillac for sale, I am interested. My guess is that they are all the same into the mid 1980's. I would also like to find one of the trumpet horns, if they were in fact available as an option.... thanks Junk.....

Timothy60
05-01-06, 09:08 PM
Thanks, Junkman! That makes a lot of sense. It would be someting electrical that is activated upon ignition that makes the best path to ground. That's why the horn beeps perfectly when the key is "off" and randomly when the car is running! Wow! Yes, that seems logical. I found 3 ground wires this evening. There may be more. The light isn't very good in my garage without getting the drop light out, so I'll remove those tomorrow in the daylight after work and clean the connections. We'll see what happens. I'll let you know. Thanks again for your suggestions.

Junkman
05-01-06, 09:19 PM
I have been giving this some additional thought. Sometimes a horn will work perfectly with lower voltage, however when full voltage is applied to the horn, it will do nothing. When the car is running, the charging voltage is higher than the normal 12 volts, and when it is parked, the battery voltage can be as low as 11 volts, but it will still function properly. I suggest taking one of the horns off and try it with jumper cables on a known strong battery on another car. Just one more of the possibilities..... Let us know how you resolve the problem... Junk........

Timothy60
05-03-06, 09:09 PM
Thanks for your help, Junkman. Tonight I removed and cleaned 4 ground wire connections I found under the hood. Maybe one of those is for the horn. I guess this is trial and error in the purest sense! I'll test the horn out tomorrow morning on my way to work, it's too late to go around beeping now.

Oh, since you know a lot about auto electrics, here's another question for you: when I was looking around under the hood of my 93 Fleetwood tonight, I noticed that the coolant level sensor wire is not connected to the coolant sensor, but someone who must have owned this vehicle before me connected this wire to the bolt that the battery ground wire is connected to. It's done very neatly like it was done in the factory. Why would someone want to do this? What do you think will happen if I connect this wire back to the coolant level sensor where it belongs?

Junkman
05-04-06, 12:00 AM
...................
Oh, since you know a lot about auto electrics, here's another question for you: when I was looking around under the hood of my 93 Fleetwood tonight, I noticed that the coolant level sensor wire is not connected to the coolant sensor, but someone who must have owned this vehicle before me connected this wire to the bolt that the battery ground wire is connected to. It's done very neatly like it was done in the factory. Why would someone want to do this? What do you think will happen if I connect this wire back to the coolant level sensor where it belongs?

My inclination to an explanation for this would be that the coolant sensor unit was defective and that by his grounding the wire, this turned the light off on the dash. Remove the wire from under the ground bolt and see if the light comes on indicating low coolant. If it does, then hook up the wire to the coolant sensor and see if the sensor is working properly. If the light continues to stay on and the coolant reservoir is at the proper level, then the sender is defective. Remove the sensor and see if it might just be stuck. If not, then just replace it....

Timothy60
05-04-06, 11:03 AM
I'll try that with the coolant sensor and see what happens. Bad news about the horn. . . it still works intermittantly when the car is running even after cleaning those 4 ground connections. I'll look for some more tonight. Maybe there are others. Maybe there's a ground connection under the dashboard somewhere? I'll find that bugger eventually!

Junkman
05-04-06, 11:15 AM
Try switching out the horns with another known good pair and if the problem persists, then it is in the wiring. If it is resolved, then it is in the horns. Also might be a problem with the horn relay, but now, I am grasping at straws. You could measure the voltage at the horns when the car is running to see if it is a voltage problem. Do the same with the car in the off position and see if they are the same. At this point, I am leaning toward a bad relay, or the relay not being properly grounded. If all else fails, then you might just have to find the services of a auto electrical technician....

Timothy60
05-08-06, 08:23 AM
Horn is frixed! Thanks, Junkman! It was the ground wire near the battery. I removed that strange ground wire from the coolant sensor (that shouldn't have been there at all), cleaned the connection, tightened the bolt and . . . the horn works perfectly! Thanks for your help; that was a very annoying and unsafe problem. Good job!