MGB HELP, my horn does not work!

[jjroth63]

Hi,

My 1966 MGB has been converted to a negative ground, with an alternator.

My second priority is:

The horns do not work, the wires are marked but disconnected. When I connected them, the wires got hot and the horns tried to sound. I unplugged them, thinking there must be a constant ground issue.

When I test the wires at the horns, the purple wire has 12v power, The purple wire goes to the fuse, the purple/ black disappears and comes out of the steering column. I think that this wire was shorting inside the steering wheel.

I tested the horns with a 12v battery and they work.

I pulled the steering wheel and there was an bad wire connection. The purple/ black wire is too short inside of the steering column to make a proper connection to the horn switch. I will probably have to pull the purple wire back under the dash and splice in a new piece to give me the proper length.

With the purple/ black wire not touching anything, the horns are not sounding, because it is not shorting out to ground.

Is this horn switch going to work? how does is go to ground to complete the circuit?

Where can I splice a new length of wire?

Am I thinking clearly to fix the horns?

Thanks,

John
Chicago

 

[DrEntropy]

The horns don't care about polarity. They work with 12V to them and depend on a ground at the horn button to work, so if the horn push is an open circuit until you push it, then closes to a ground point (the steering column), things should work.

 

[jjroth63]

The horns don't care about polarity. They work with 12V to them and depend on a ground at the horn button to work, so if the horn push is an open circuit until you push it, then closes to a ground point (the steering column), things should work.

thanks, I get that.

I had to rebuild the switch in the steering wheel so it would make contact when depressed, but not when it is not depressed.

How can I get slack in the purple/ black wire to connect it to the switch?

I cannot find where it comes out of the bottom of the steering column.

 

[DrEntropy]

Not sure what you've got there, the outward appearance is of a 1968 or later chassis/body car. Door latches/handles ~could~ be a late '66. The windshield is definitely '68 or later. The purple/black wire should have been in the bundle under the dash coming from the engine bay, connected thru a "brush and bushing" at the steering column top, along with the turn signal switch & wiring. That aftermarket wheel is different.

 

[jjroth63]

Not sure what you've got there, the outward appearance is of a 1968 or later chassis/body car. Door latches/handles ~could~ be a late '66. The windshield is definitely '68 or later. The purple/black wire should have been in the bundle under the dash coming from the engine bay, connected thru a "brush and bushing" at the steering column top, along with the turn signal switch & wiring. That aftermarket wheel is different.

The dash looks like a 66, I am not sure about the rest. The dash is covered in a vinyl wrap, it looks terrible.

 

[DrEntropy]

The early dash was under a "safety" one in '68 and maybe some '69 cars, padded with foam and plastic to meet US crash standards. That may be what you've got, with the covering removed.

The dash was the same from the first MGB to '67, small rearrangement of headlight, choke cable and washer pump in '67. After that it was the padded ones.

Fundamentally the early panels were like this, the lower panel is one I made for different instruments to be period correct.

 

[jjroth63]

Well, I figured it out, either I am the smartest man in the world or you guys were holding out on me. It almost seems like a joke that I did not receive the answer that I needed to solve my horn switch problem.

There was a purple wire that was too short to connect to, I needed to extend it to the switch. I could not find a way to get any slack. I figured it must somehow connect to the copper bushing. After thinking about "what's the worst thing that could happen", I decided to pry the "crimped" end of the bushing to unlock it from the shaft. I was able to remove the bushing and locate the other end of the purple/ black switch wire, it has a spring on it which supplies pressure to drive the end of the wire against the inside of the bushing. I was able to pull the wire out of the housing and solder an extension onto it and heat shrink the joint. I cleaned, lubed and reinstalled the mechanism and the horn worn properly!

Hopefully this can help someone.

Now on the the turning signals, the seat webbing and stereo speaker.

 

[DrEntropy]

Well, I figured it out, either I am the smartest man in the world or you guys were holding out on me. It almost seems like a joke that I did not receive the answer that I needed to solve my horn switch problem.

Considering it's likely been forty years since I've had a problem on any customer's early MGB with a horn button issue, and not willing to disassemble my own now, all I will say is: glad you found it and fixed it. But I don't think anyone here was "holding out" on you!

 

[jjroth63]

Considering it's likely been forty years since I've had a problem on any customer's early MGB with a horn button issue, and not willing to disassemble my own now, all I will say is: glad you found it and fixed it. But I don't think anyone here was "holding out" on you!

Originally, I was trying to find the other end of the wire, I eventually did.
I am sure you are correct; I was just surprised that it was a relatively easy fix and no one else has had the same problem.