Low air alarm

^^^what he said^^^

 

I have 93 FLD that I am having an issue with the low air alarm sounding when the psi drops to about 85. (not sure about the exact pressure due to the gauge not having any other numbers other than 60 & 120). Any ideas on where I can look for the potential source - sensor?

If it is a sensor, where would I find it? This is a new to me truck and I am new to trucking so please be patient with my ignorance.

 

kenwortht660 yes i would replace the air pressure switch it is located behind where your trash can is. and on how your air system works, here we go.. air comes from the air compressor to the air dryer, then to the wet tank (excess water is traped here), then to the primary tank (green needle) and to the secondary tank (red needle). from thier it goes to all the air components on the truck. all of your air switches for your freightliner are in a manifold behind the trash can. switches get air after the air tanks, not before the dryer


joecitizen your air pressure switch should be behind the steering column (lower part) its a pain to get to

 

kenwortht660 i forgot to metion tha the primary air switch is the 2nd row down farthest to passanger side and secondary air switch is bottom row farthest to the passanger side, u get trash can taken out u will see what i mean, thier is a total of 10 or 12 switches

 

FYDA FREIGHTLINER CINCY, thank you for the response...

question, based on what i am experiencing, the air pressure switch is what i should be looking at to replace/test?

the alarm is kinda faint, but noticeable & the light turns on and is dim, yet when the pressure is back up to about 120psi the light turns off & so does the alarm. if i build psi (120) and turn off the engine and then turn the key to the on position the alarm sounds? is this normal?

(would you pm me the price for this switch? need to get the truck ready for my test...)

 

yes that is normal, i don't think the switches are more then 20 a piece, make sure when u get the switches they say N C on them that means normaly closed, alot of parts guys get them mixed up..

 

FYDA FREIGHTLINER...

went to l.a. freightliner this morning to purchase the low pressure switch. I was given part # FSC-1749-1907 which is normally open and has a red strip around it. i told them i needed a normally closed switch as you advised, they told me this is the switch, the brake and something else where normally closed.

i went ahead and purchased it and will be on the way to the yard to install it here shortly. could you provide a part number i should purchase or can we work something out so i can purchase the switch from you?

thanks for your help...

 

moisture around the visual bar will cause the light to come on dim and stay on. Fought that in my 98 pete for a long time replaced all the sensors a couple times and the visual bar and found out there was water getting in thru the windshield seal causing the light to go haywire.

 

bullhauler, thanks for the info...

i got the switch in and the problem seems to have gone away. (thanks for the solution FYDA FREIGHTLINER)

I now understand why freightliners are called frieghtshakers (i think anyway), my dash is absolutely obliterated. first time i have taken the dash apart and EVERYTHING is broken. i basically have nothing to screw anything into!

the individual who owned it before me, well, can you say mickey moused? there were wire strands "jumping" between the electrical connections of the air pressure switch, then the dash module (dont know the technical name for it) had the actual buzzer removed! geez... i hope i have the problem solved.

this truck has gotta be right for my driving test!

thanks all for the info....

 

kinda makes u wonder what else they had done