Low air alarm

i know this is an old thread, but i finally found the cause, the wire connector to the sensor was loose so the connector would wiggle just right and cause the buzzer to sound or light on dash to go on. i left the ignition switch on and started uplugging wires out of frustration one day.

 

Freightliner FLD 120, low air and buzzer sometimes stay on even though the air pressure, both systems, is good. The buzzer used to quit always at about 90, but the warning light would seem to extinguish slowly, like the intensity was diminishing. Check wiring, seems okay. Do the sensors fail slowly like this?

 

It could easily be a bad "sensor" which is really just a switch. They are very cheap and easy to swap in a FLD, so that would be my first attempt to fix it.

 

Hey guys im having a similar problem, My LOW air warning wont cut off, i replaced ALL the air sensors behind the steering shaft, checked for shorts as well. Is there another AUX sensor or something? 1999 Freightliner Condo FLD 3406E CAT

 

Just went through a similar issue on my truck, and I dont know what the correct term for the part I fixed was. For my truck the buzzer would stay on and it would air up the whole system with the exception of one "part" of the system. The splitter, air to the seat, stuff liek that wouldnt work, the buzzer would stay on and the truck would fully air up, kick out and work properly.

Anyways this part I fixed was a tube with a spring and a ball bearing in the end, with a knob on the other end that you could screw in and out to restrict the flow of air into one of the tanks. (hopefully someone can come correct me with the terminology!)

I took that part apart, cleaned it out, readjusted it, and the buzzer cut out when it was supposed to, and everything worked like normal again.

 

I fixed my issue it is a "NO" (normally open) Low-Air switch. gotta get it at the dealer

 

Most every low air sensor I have ever seen is in the lower section of the gallery in an FLD it has one wire going to the two sensors no pressure they are NC if tested at pressure they are NO. If you test at the parts counter with an OHM meter it will show less than .1 OHM's. it should trip at 60 lbs to an open circuit.
Just a thought!

 

Yeah thats what puzzled the truck dealer, after alittle digging we found that some freightshakers are NO with no pressure. Had a clerk at fleetpride tell me i didnt know what i was talking about. But its called a red stripped low air warning switch "NO" factory replacement

 

The wiring grounds the circuit, if you take a test light there will be power to the wire, with low preasure it grounds out and the buzzer rings.

 

My 04 Columbia just started going of while I was driving the other night, then shut off when u stopped. I shut her doable for the night & moved it once the next day, no issues. No its on permanently, but only when I put the vehicle in motion, forward or reverse... and when I pump down to 65 psi, but swiftly goes out like it's suppose to, upon building back up.
It's pretty consistent so far. All fluids are up. I'll open it up & check connections in the morning & keep y y'all posted.