low pressure air alarm not working properly, ADVICE APPRECIATED

Discussion in 'Trucks [ Eighteen Wheelers ]' started by TowHaul, Dec 17, 2017.

  1. TowHaul

    TowHaul Medium Load Member

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    NOW THATS WHAT IM TALKING ABOUT! I just got up and going to brew some coffee, id like to finish this problem off pnce and for all today...i am stubborn, driven (and NOT mechanically gifted)....but usually get whatever mess fixed in the end :)
     
  2. lilillill

    lilillill Sarcasm... it's not just for breakfast

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    First, make sure this is the dash cluster you have or at least that the connectors on the back look the same.

    IMG_1201.JPG

    This is the cluster tilted back out of the dash. I've removed the blue wire retainer just for clarity.

    IMG_1202.JPG

    This is where the wire on circuit 18 connects to the ICU

    IMG_1203.JPG

    And closer up...

    IMG_1204.JPG

    If this wire is disconnected from the cluster, the low air warning light and chime should come on and stay on. If you ground this wire, the light and chime should go off completely.

    If it does not work like this, then there is likely a problem with the cluster itself.

    This is how to wire it so it works like it should...

    fl_low air.png
     
    TowHaul Thanks this.
  3. TowHaul

    TowHaul Medium Load Member

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    BRILLIANT! my cluster is indentical. I am varnishing wood in sleeper atm will attack this problem with your suggested diagnosis in anhour or two and report back. Again wow, THANKS.... if i ever get this beast rolling ill buy you steak dinner
     
  4. lilillill

    lilillill Sarcasm... it's not just for breakfast

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    This is what the low air chime should sound like during a self test. If it doesn't sound like that, possibly the chime in the ICU is bad.

     
  5. TowHaul

    TowHaul Medium Load Member

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    Dash looks identical but wiring on backnside is different. All yellow wires, two bundled sets. I cannot identify tge wire you are indicating.
     
  6. TowHaul

    TowHaul Medium Load Member

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    Yes icu chime correct. Waaaaay too quiet when truck running.
     
  7. TowHaul

    TowHaul Medium Load Member

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    Hooking it up to the eternal buzzer with air switches primary and secondary running parallel i now get 6.8volts to buzzer....much worse than the 10.5 i was getting befor (which was too weak to power buzzer or light)
     
  8. TowHaul

    TowHaul Medium Load Member

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    CORRECTION, hooked up to external buzzer it is at 6.9volts unhooked 10.6v. Parellel schemtic is correct but voltage still too weak
     
  9. TowHaul

    TowHaul Medium Load Member

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  10. TowHaul

    TowHaul Medium Load Member

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    Ihave to literally flick buzzer to turn it on