How do I replace the horn wire in the steering shaft?

[gottaluvit]

Okay, now the horn. I looked all over the search function to find lots of posts on dueces but no breakdown for 5 tons. Traced my lack of horn to the wire in the shaft. Got 24v at the solenoid positive side. (wire 25) Unplugged the wire from the box at the bottom of the steering column and the solenoid clicks when I ground it. Checked for continuity from wire in column by horn button to the post on the box at the bottom of the column since solenoid don't click with horn button and no continuity. So I took the little box at the bottom of the column off and put one tester wire on the brass/copper that is part of the shaft and the other on the horn button wire and still no ciruit. Sound to me like that wire in the shaft is broke or unhooked. I have the column out and don't see how to take it apart to replace that wire.

Any help would be greatly appreciated.

Or a great deal on a full shaft with a good steering wheel and wire inside (working). My wheel is ALL cracked up and hideous so that might save another headache.

Thanks,
Jim

 

[Rmtaunton]

If it's older the power is constant ,,, the ground makes the connection ... I.e. Horn blow

 

[gottaluvit]

Right. Got the 24v at the solenoid. I put in op that it was wire 25 but it could be 26. Regardless it's the one that isn't the same as the wire number for the ground at the column. It is switched (only on when battery switch is on) and not always on like some I have read about are, but the ground wire in the column is my issue. I need to know how to get the column apart to replace/repair that wire.

 

[gottaluvit]

If this pic loads it is my helper tracing wires.

 

[MyothersanM1]

I replaced the wire in an M818 steering column. I know we are talking about two different trucks, but I think their construction may be similar. The whole inner shaft can removed on my truck which facilitates changing out the wire. I am attaching a copy of the instructions that spell out the procedures for the older trucks. Maybe it will give you some guidance for your truck.
Sorry for the sideways format...

View attachment Horn Button Instructions.pdf

 

[gottaluvit]

MyothersanM1: Thank you very much for that. I had to print it so I could read the sideways pdf but well worth it. I believe I understand what they are saying. I will tear into that tomorrow as I have time. I figure some heavy yet flexible wire with rubberized insulation should do the trick and I will solder the connection that is currently on the existing wire to the new one. This truck is nice but loaded with little issues all over. I hope after I get it legal and can road test it a good bit that there are only these "little" issues. Just read about air hoses crossed up on a lot of these M939 series trucks affecting the xfer case so I reckon I better be inspecting them too.

Again, thanks a lot.

Jim (and PG the helper).

 

[MyothersanM1]

Sorry for the vertical format. I apologize for any neck pain

And, here's my helper...

 

[juanprado]

I am not a electrical guru but the m939 series have a high failure of the diode in the ground wire in the harness by the horn. OE diode is in a plastic bubble in the ground wire.

Search on here as another member posted the diode which is cheap and available on flea bay. Solved my horn problem.

Good luck finding the gremlins

 

[MyothersanM1]

M-809-series do not use the diode. It's just straight wired. Any clue as to why the M939-series added that?

 

[m16ty]

Sorry for the vertical format. I apologize for any neck pain

And, here's my helper...
View attachment 560945

Mine had a little trouble checking the belt tension (while running). WARNING GRAPHIC http://www.steelsoldiers.com/showth...gine-compartment-CAT-LOVERS-BEWARE&highlight=

 

[gottaluvit]

MyothersanM1: That looks like a nice helper. Probably gets in them places you can't so easy. No help here on what the purpose of the diode is. Just more trouble.

Juanprado: I think I read where when the diode goes your horn will blow with out shutting off until you unhook it. Hard to tell if that's the only issue it causes, like just not working. Is there a way to test the diode?

Thanks,
Jim

 

[gottaluvit]

M16ty: Sorry about your cat. Not a good way to go. You have made me check close before firing up the old beast. Don't want to see poor PG get done in that way.

 

[gottaluvit]

Well, I have tried following them directions and I can only get that bearing flange to move about 1/4". As I tap one side the other goes back in the jacket. Seems like the bearing may be seized to the gearshaft. Any ideas from here? I really don't want to damage anything considering I have no backup on hand (or anywhere). Anyone have an extra column with a working horn and a good steering wheel for sale? R&R sounds like where I am now or putting a rigged horn button on the side of the column.

Any help would be appreciated.
Jim

 

[jarhead1086]

When I fixed my horn I replaced the box at the bottom of the column with a new one without a diode. I don't think its necessary. My spring loaded ground wiper was worn out and messed up by the same E-1 that jacked up my airlines. What I also found out is that the screw lengths are critical in their respective positions. I got ground when I steered to certain positions. Put them in the right spot and it now works great. I would rather bust tires all day than to crawl under that dash. Takes a while to unkink myself.

 

[gottaluvit]

Jarhead1086: glad you got yours figured out. That would have been a joy to figure out. I hate trying to get up under there and stand on the step at the same time. Rough.

I have decided it's gonna get a cheap horn button mounted on the side of the column. Put the column back in and touched that wire that goes into that box to the ground but still no horn sound. Is there something in that box that is necessary to be inline before the circuit gets grounded? I heard clicking under the dash and my air pressure was up.

Jim

 

[juanprado]

MyothersanM1: That looks like a nice helper. Probably gets in them places you can't so easy. No help here on what the purpose of the diode is. Just more trouble.

Juanprado: I think I read where when the diode goes your horn will blow with out shutting off until you unhook it. Hard to tell if that's the only issue it causes, like just not working. Is there a way to test the diode?

Thanks,
Jim

I am sure there is a way to test but I am not the right guy with a multi meter....
Mine did sometimes "stick" and stay blowing and then stopped all together.
I went with the scorched earth theory and replaced the diode, horn, solenoid as I have real good access to scrap trucks and easier to bolt on/off. I even had pulled a horn button but did not need to do that.

see this for diode:
http://www.steelsoldiers.com/showth...g-button-wont-stop-until-turn-shut-down-truck

 

[jarhead1086]

I just unplugged the rubber mil connector and hooked an alligator lead to the male pin coming out the top of the green box and put my other lead to the screw head holding the ground lead at the top edge of the box. It measured open. When I depress the horn button it drops down to 10-15 ohms. You can check the horn button by itself the same way. Open you windshield and measure from from the female mil connector to the horn. I have a hard time believing the wire in the column could open. The box takes a few hands to get put in place right, but my bet is that the box is messing with you. My horn also had one of the two sides corroded shut. Looked like a copper check valve. The corrosion made it act flakey even after it broke loose so I replaced the horn. You have to get your horn working as a back up when your air brakes quit working.

EDIT: I think the mil connector gets kicked often and my old box had issues with a poor mechanical connection between the male pin and the box. It was loose.

 

[gottaluvit]

Nice pic jarhead. Yesterday I got my air pressure up and cracked the line to make sure I had air at the horns and good to go. Hooked up the continuity tester up to the 25 wire at the box in jarhead's pic and the 25 wire at the horn and tested to be a good wire. So I ran a wire from the 25 at the box in jarhead's pic out by the actual horn so I could hear what was going on as I connected it to the chassis and the horn solinoid did click and no sound so I just kept touching it to the ground and it eventually started sounding off a little louder with each touch to ground until it eventually sounded like a normal horn. Now all I have to do is buy a cheap horn button to mount on the side of the column and I will be legal until I make it to the next show and hope to find a deal on a complete column, or get lucky in the classifieds. Still holding out for one with a working wire to the brass that the wiper in that box contacts and with a good steering wheel and horn button. But for now I will be legal in that aspect. A lot more going over this truck before the title gets here anyway.

Thanks,
Jim