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TR5/TR250 Horn Problems Late TR

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glemon

glemon

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I have a TR250 and the steering column seems to be live (grounded?) so that it goes off intermittently when pressure is applied to the steering shaft. I checked to see if the purple horn wire was framed in the column. It is not, nor is there a problem with the horn contact ring in the column.

I put new bushings in the column several years ago in a quick fashion by driving them them on without taking the old ones out. I am trying to remember exactly how, but that is about the extent of my memory of it. Anyway, the shaft is still tight in the column.

I am trying to figure out how the column is grounded, but I am also trying to figure out how it isn't grounded since it is a metal column in a grounded metal car. There are aspects of the horn wiring I don't think I understand.
 
Not sure I'm following this, but isn't the steering column grounded, (like the body and chassis)? Unless a part is isolated/insulated, seems that most metal in the car is a ground (and thus, grounded). I think "live" means there's a direct line to the battery + post (on a negative ground car).
 
My understanding is the horn circuit is activated by connecting the ground circuit through the horn push that completes the circuit that comes up through the steering shaft that is why you have wires on the rubber couplings on the shaft) to a wire on the horn ring that then runs to the horns.

Misstatement when I said the column was live, I meant grounded.

My understanding is the column isn't grounded as if it was you would get a beep when the steering hub hits the column if you exert some pressure on the wheel, but like you I am struggling to figure out how the metal steering column wouldn't be grounded.
 
glemon said:
My understanding is the horn circuit is activated by connecting the ground circuit through the horn push that completes the circuit that comes up through the steering shaft that is why you have wires on the rubber couplings on the shaft) to a wire on the horn ring that then runs to the horns.

Misstatement when I said the column was live, I meant grounded.

My understanding is the column isn't grounded as if it was you would get a beep when the steering hub hits the column if you exert some pressure on the wheel, but like you I am struggling to figure out how the metal steering column wouldn't be grounded.
Click to expand...
The column is not of itself grounded -- because the couplings between the metal sections are rubber. It is grounded because you should have placed a braided wire with loops on each end to carry that grounding from metal section to the next metal section. This then provides a ground at the steering wheel. The purple wire is the hot horn wire looking for a ground to make the horns honk.
If you are having the horn seemingly honk on its own then you are having a problem with the purple wire and the ring inside the steering wheel. Look there.
Charley
 
Thanks Charley, that helps. I have checked the purple wire that runs through the little shunt under the column as well as the ring, they all are fine. However, if I hit a bump, or lean on the steering wheel such as grabbing to help me get in and out of the car I get a little toot, or sometimes a big one. It definitely seems to be related to movement of the steering wheel. I have the wires (replaced) to ensure electric flow through the rubber coupling.

The horn works when intended, it just also works when not intended.

I have had TRs for decades, have pretty much figured everything out and gotten it to work correctly and consistently except for the GD horn. Had similar problems on my TR4A
 
I think that it is certain that there is a fault in the purple wire OR the horn button/spring tracer.
Back in the 60's, I resorted to having a bare wire that could be grounded to the dash to honk the horn.
The whole car was a rolling electrical problem...
Mad dog
 
Exploring whether it could be the horn button, I have an aftermarket steering wheel, I may just refit the stock one and see what happens, but I think I had trouble with that one too (I found a similar questioned I posted in 2017 with the stock steering wheel).
 
Think I have figured it out
IMG_20240719_215837063_HDR.jpg

Look at the inner part of the horn ring above, and the inner circle of the steering wheel hub below. Methinks I will grind a bit off the hub and see what happens. Thanks for pointing me in the right direction
IMG_20240719_215845725_HDR.jpg
IMG_20240719_220641271.jpg

Same thing going on with the stock steering wheel, seems to confirm the issue
 
Ah, I think you have the correct idea. I also had a problem with aftermarket TR4 steering wheels. I kind of recall that I ground off a bunch of that lower ring to correct my problem.
Charley
 
And once again the AM parts Demons strike terror and confusion.
Did you know that for several years the only AM 3 prong flashers sold in America
were not only from the same supplier, but could only flash on one side?
Bad from the factory. QC had never tested ONE to see if it worked.
Mad dog
 
Buttoned back up and all working right now. I have been struggling with this issue for years. My stock wheel did it too. For whatever reason the stress of autocrossing seems to pull the wheel and steering column together no matter how hard I bolt down the clamp under the steering column.

Because of how it seemed to be occuring I thought it was the hub rubbing on the column, but the inner hub on the contact ring (which makes much more sense). Thanks for pointing me in the right direction.

I got in the habit of unhooking my heart runs when I autocrossed, but then on the street I realized I don't have a functioning horn, which I didn't like because I think half the traffic on the road doesn't seem my little old car.
 
Greg- I think you’ve sorted this but I was having the same issue and it drove me crazy - the fix is to get more distance between the hub and the ring. You can do that by loosening the clamp that ties the inner and outer steering columns together and pulling the steering wheel assembly away slightly. No need to modify the hub itself.

Randy
 
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