1971 My horns do not work

[ratlifcs]

My horns do not work. The horns themselves are good, and the switch (squeeze the steering wheel rim) is good. Wiring diagram leads me to the "14401 assembly," which is, I believe, the circuit breaker assembly. Where is it, and how do I troubleshoot it? Any other ideas?

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[cougarsunlimited]

My horns do not work. The horns themselves are good, and the switch (squeeze the steering wheel rim) is good. Wiring diagram leads me to the "14401 assembly," which is, I believe, the circuit breaker assembly. Where is it, and how do I troubleshoot it? Any other ideas?

Do you have the optional speed control?
If so, the horn relay could be bad.

 

[ratlifcs]

Do you have the optional speed control?
If so, the horn relay could be bad.

I do not have cruise control. Do only cruise control equipped cars have a horn relay?

 

[cougarsunlimited]

I do not have cruise control. Do only cruise control equipped cars have a horn relay?

Yes, only cruise control equipped cars use a separate horn relay.
Although, the four-note horn option for 1968-69 Thunderbird also used a horn relay.

 

[cougarsunlimited]

The 14401 assembly is the main under-dash wiring harness.

Have you checked the horn spring-loaded copper contacts under the steering wheel?
These contacts are part of the turn signal switch. These wear down over time and fail.

Try checking the yellow and blue/yellow wires at the turn signal switch connector.
The yellow should be +12V all the time.
The blue/yellow should be +12V when the steering wheel horn switch is squeezed.
The blue/yellow directly drives the horns on non-cruise cars.

 

[ratlifcs]

The 14401 assembly is the main under-dash wiring harness.

Have you checked the horn spring-loaded copper contacts under the steering wheel?
These contacts are part of the turn signal switch. These wear down over time and fail.

Try checking the yellow and blue/yellow wires at the turn signal switch connector.
The yellow should be +12V all the time.
The blue/yellow should be +12V when the steering wheel horn switch is squeezed.
The blue/yellow directly drives the horns on non-cruise cars.

Thanks! I'll check the wires as you suggest. I agree with you that the 14401 assembly is the wiring harness -- it took me a while to figure that out. Looking at the wiring diagram, power for the horns passes through a "circuit breaker assy. part of 14401 assy." Any thought on where I can get a circuit breaker assembly?

 

[cougarsunlimited]

I dug out the 1971 Thunderbird diagram. It combines the diagram for the cruise control horn and standard horn switch into one picture, area K80.
It shows connections for the horn relay with cruise and the standard horn switch.
To interpret it correctly, you have to know that the horn relay is not used with cruise.
Sorry for the quality, my scanner won't scan 11"x17" pages.
It also shows the 30A circuit breaker.
Apparently, the wire colors changed in 1971 to blue (horn side) and yellow-blue dots (12V feed).

The typical 30A circuit breaker is available from AutoZone or O'Reilly.
It is located on the inside firewall, just above the passenger foot well. There are several in this location.

 

[ratlifcs]

Wow, sir! Many thanks! what you tell me checks with my knowledge while filling in a huge gap! I'll go to the AutoZone and O'Reilly web sites to buy the circuit breaker.

I am wholly committed to keeping my 1971 Tbird roadworthy. My parents bought it new in early 1971. I took possession when my parents moved overseas in 1980. I drive it about once a month to keep it fresh in homage to mom and dad.

 

[ratlifcs]

Thanks! I'll check the wires as you suggest. I agree with you that the 14401 assembly is the wiring harness -- it took me a while to figure that out. Looking at the wiring diagram, power for the horns passes through a "circuit breaker assy. part of 14401 assy." Any thought on where I can get a circuit breaker assembly?

Sir, You mentioned, "Have you checked the horn spring-loaded copper contacts under the steering wheel?" I removed the steering wheel, cleaned up the spring-loaded copper contacts and lubricated their springs, and polished the metal rings they contact on the steering wheel. Horns work now! Thank you so much!