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Topic: Air horn solenoid valve issue? (Read 1362 times) previous topic - next topic

Air horn solenoid valve issue?

I recently purchased a 1991 U300 and the air horn worked reluctantly at that time, at least enough to get an inspection sticker. Now after traveling around a few thousand miles it doesn't work anymore. I think the horn button on the steering wheel is still making electrical contact because it still interferes with the backup camera's screen when I press the button just like it always did when it worked before. I presume the solenoid valve is stuck or something. Where is the solenoid valve located? I'm driving from Nashville to Maine next week and I have to go through NY, NJ, and MA traffic on my way there! (laugh)... and of course I'll have to blow the air horns for my sister's kids when I get there... so this is important ;)

Scott

Re: Air horn solenoid valve issue?

Reply #1 –
Mine just quit on last week's trip. Same problem. Was going to go under and search for the solenoid but figure others must have had the same problem.

Pierce

Re: Air horn solenoid valve issue?

Reply #2 –
I always do a search to see if someone else posted the answer previously, but I didn't see any similar questions, so I posted this one.

Re: Air horn solenoid valve issue?

Reply #3 –
For your coach, air horn solenoid is under front access door below windshield on driver side. It is on air tank which is next to small air compressor.

Others have had to replace their solenoid, too.

Re: Air horn solenoid valve issue?

Reply #4 –
I drove from Tennessee to Maine and discovered that my voltage fluctuates dramatically and the solenoid valve for the air horn won't open when the voltage is low. I presume the coil is weak or the valve is sticking or something. It works sometimes during the day when the voltage is high, but never at night when the lights are on and the voltage is low. My solenoid valve is located on the back of the air gauge in the dashboard. There is no isolation valve so I'll have to drain the air system to remove it. It's a 12 volt system and I suspect most trucks have a 24 volt system, so I would need to pay attention to that when buying a replacement valve... if I were to replace it that is... but I'm thinking of installing an ordinary valve with a pull chain and using the electric horn circuit for a Model A Ford "Ooogah" horn I've had for many years... I dunno, just thought it might be fun... and my air horn would work with the pull chain regardless what the voltage was.

Re: Air horn solenoid valve issue?

Reply #5 –
I think you would be better served reducing your voltage fluctuations. Check ground or run a new ground wire to solenoid & check 12-volt positive connections.

Re: Air horn solenoid valve issue?

Reply #6 –
Yeah, I'm trying to figure out why the voltage gets so low. The only thing I've noticed is the alternator belts get loose often and I have to tighten them if it gets to the point where I can turn the alternator by hand. I don't want to over tighten the belts but I don't want them slipping either. I don't know why they need to be tightened so often. I replaced them with a new set of belts even though there wasn't anything wrong with the belts that were on there. I kept the old belts just in case I need them in an emergency. The voltage regulator and wires all look fine with no corrosion or heat discoloration or looseness... so I don't know... I have all new batteries and they were tested by Foretravel in Nacogdoches and everything worked fine.

Re: Air horn solenoid valve issue?

Reply #7 –
Replace belts with Gates Fleet Green Stripe belts. If you have two, always replace as a pair. Tighten until you can JUST roll the belts with your fingers 90 degrees midway between alternator and drive pulley. Check a couple hundred miles after first installation and then as part of a pre-trip checklist.

Belts should not be getting loose. Heat from slipping causes them to glaze and stretch and then slip more. Major brands like Gates or Dayco should not stretch.

If you have time, order online for 50% savings over auto/truck stores.

Using a strong light and magnifying glass, check for any cracks, especially at bottom of "V" notches. Replace if any noticed.

Peirce

Re: Air horn solenoid valve issue?

Reply #8 –
Have you checked carefully for bracket cracks?

Re: Air horn solenoid valve issue?

Reply #9 –
Turns out the solenoid valve was bad. I ordered a new one from Amazon, and they're also available on eBay, for about $40 from either place. I drained the air from the entire system by opening the ball valves to blow the moisture out of the tanks, then pumping the air brake pedal until it was completely empty, then I replaced the air horn solenoid which is on the back of the air pressure gauge on the instrument panel. My air horns work now. The problem had little or nothing to do with the voltage. Thanks for all your help my friends... ^.^d

Scott
 

Re: Air horn solenoid valve issue?

Reply #10 –
Our experience shows the Gates Belts to be far more reliable than the Dayco, Dayco tend to stretch easy and when reved up, they will depart and/or turn over.
I only use a Dayco in an emergency, but replace it with a Gates asap.
Dave M