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Can anyone help me located the technical manual for this assembly so I can find either how to repair or replace parts on the horn? As you can see from the picture, wiring inside the dome has burnt.

The back of my horn is domed with a hex-dome nut that holds the dome to the internal assembly. The data plate on the front states:
The Electric Auto-Lite Co.
Toledo, Ohio — Made in USA
24v HX-4004-UT Type 2. Class A
Ordinance Piece 7728341

The horn bracket reiterates the Ordinance No. as well. While I’ve reviewed TM 9-1825B, therein I found the HX-4001UT & HX-4002UT as the only 24v horns. I don’t see anything on the correct horn let alone component part numbers.

Here are more views of the horn components

The Army didn't spend much money on Horn repair manuals. Most were military XB3 supply code items which were deemed non-repairable/non-rebuildable and thrown away when unusable. Most had no parts manuals either. The assumption the Army went with on the many later variations of the HX400XUT series that came available after November 1952 and were for the most part listed in the applicable military vehicle parts catalogs were extremely similar and could be repaired with the basic 1952 info. I have several dozen late 50's thru 90's Civilian Autolite/Prestolite Service and parts manuals none of which offer any help with the HX series horns. I suggest you use what's currently available in the 1952 TM 9-1825B on pages 366 thru 371 and follow their procedures and if any gapping holes arise post the specific repair questions here.

Wes,

Thanks for the information. I figured that it was categorized as non-repairable in the AMDF. However, I believe if i can find the dome that has Douglas connections I can rebuild it.

Plenty of Douglas connectors, kits and tools on the market still.

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Wes,

Thanks. I found a Douglas crimping tool on eBay, which I’m sure I will need for more parts of the larger M38A1 project.

Jeff

If you google vintage horn repair there are several options there too. I know there are more 12 volt 30's Ford Model A horn restoration services out there but they may be willing to work on yours or know someone that does.

Thank you. I found a manual from auto-lite. While it’s not specifically for the HK-4004-UT, it has various earlier models from which I could extrapolate.

I emailed a copy of the specs for your horn to you. Do you have the Army Manul for the Autolite Horns and electrical TM 9-1825B dated 1952. If so the repair info there should work and the correct specs are all you needed.

It would be useful to many if those specs could be posted here for all to see and use.
Thanks!

Ron, the file is already here. The link above is in our Mjeeps photo albums. In the old days of this web site those photos and files could be very easily attached to our posts but todays system doesn't seem to cooperate much.

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