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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: rwc on November 24, 2012, 07:52:48 AM



Title: Low Air Pressure sensor
Post by: rwc on November 24, 2012, 07:52:48 AM
102D3 Low air pressure light will not go out. I have greater than 120lbs pressure. Where is the pressure sensor located? what does it look like?  I have the books and am unable to locate them in the books.  Thanks for any help  Rod


Title: Re: Low Air Pressure sensor
Post by: luvrbus on November 24, 2012, 08:00:37 AM
It should be on the supply line to the brake pedal either about 2 inches round with 2 wires or a rectangular shape with 2 wire easy to test by jumping the terminals or test light

good luck


Title: Re: Low Air Pressure sensor
Post by: Dave5Cs on November 24, 2012, 08:29:49 AM
Book shows the spare tire area coming off the accessory tank line.

Dave5Cs


Title: Re: Low Air Pressure sensor
Post by: Len Silva on November 24, 2012, 08:55:48 AM
I'm not familiar with you bus but there may be more than one switch in parallel.


Title: Re: Low Air Pressure sensor
Post by: John316 on November 24, 2012, 09:09:33 AM
Rod,

On your D3, I think it is on you accessory tank. At least, I think that is where ours is located. To me it doesn't make sense, but that is where they put it, I think. Basically, the two needles on your gauge show brake pressure. The low air alarm should be on you accessory tank, if yours is like ours. That will be under your front Jbox, lower panel, next to your spare.

That being said, Clifford knows what he is talking about. So I just offer another place to look, not a different place.

John


Title: Re: Low Air Pressure sensor
Post by: luvrbus on November 24, 2012, 09:17:32 AM
 I don't where MCI put theirs for sure but it's probably not the switch causing the problem if he has power going in and coming out,MCI did some crazy circuits with relays and parallel switches that one should be hot on both side till pressure builds then hot only one side  lol 

Like Len said it could have more than one in the circuit for the dash light does the buzzer quit ? I thought the one at the tank was for the buzzer


Title: Re: Low Air Pressure sensor
Post by: John316 on November 24, 2012, 10:05:49 AM
See what I said, Rod. Clifford knows what he is talking about.
I thought the one at the tank was for the buzzer

Clifford, that is on the buzzer. On our bus, the buzzer is tied to the low air light. You nailed it. MCI does some strange things.


Title: Re: Low Air Pressure sensor
Post by: rwc on November 24, 2012, 10:10:35 AM
Thanks Clifford I will look for something that looks like that In the rear junction box the diagram shows a low air sensor but I cannot identify anything that looks like that will check front by brake valve.  Rod


Title: Re: Low Air Pressure sensor
Post by: rwc on November 24, 2012, 05:44:43 PM
Do these pictures show a low air sensor? There are two on brake valve and three others all in spare tire compartment. Jumping terminals did not seem o change anything but possible I was not getting good contact. Nothing on the air tank has wires.


Title: Re: Low Air Pressure sensor
Post by: luvrbus on November 25, 2012, 06:59:50 PM
The unit in the tee in the 3rd photo should be the low pressure sender one sender should be for stop lights activated by the brake pedal then one should be for stop light activated by the parking brake application the rest you are on your own lol unless a MCI guy can help 

Your bus does have a dual air system I think most D series were so it will be a little different from the older buses

good luck


Title: Re: Low Air Pressure sensor
Post by: rwc on November 26, 2012, 11:25:14 AM
Thanks Clifford. That one I can find in the Book labeled switch pressure. Only found it after DaveC gave me a hint from his book.   There are two on the brake valve in the forth picture that look similar I can,t find in the book.  Rod