Apu stop working

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by 7seriestv, May 26, 2019.

  1. 7seriestv

    7seriestv Light Load Member

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    I just got this truck Monday with a tripac apu. It work fine until Thursday, it was running then the red system fault light come and it shut down. The code is AL and a symbol look like an upside down F. 20190524_140736.jpg

    The oil level is good,I check the ground on the alternator, it was slack and I tightened it, then I press the reset switch and it still doing the samething. It will run for about 5 mins then the code come up and it shut down.
     
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  3. bzinger

    bzinger Road Train Member

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    Was the cooling system recently opened up for a repair ?
    If so this can introduce an air pocket which needs to be bled at the apu .
     
  4. mhyn

    mhyn Road Train Member

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    you need new alternator.
     
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  5. 062

    062 Road Train Member

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    Actually there are a few things that can cause this.
    You need to check the voltage at the alternator first. If that’s good, then go to the box under the bunk and check the voltage on the sense wire. It should be labeled Sen. this was the problem with my apu. The sense wire was broken. You can run a new wire or make a jumper and tap off the lug beside the sen lug.
     
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  6. Rholl

    Rholl Bobtail Member

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    Need to read the codes
     
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  7. lilillill

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

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  8. 7seriestv

    7seriestv Light Load Member

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    I will check that out, thanks for the information
     
  9. 7seriestv

    7seriestv Light Load Member

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  10. Devonbrett

    Devonbrett Bobtail Member

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    Sep 2, 2019
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    My comfort pro keeps saying main engine interlock and refuses to even try to start. Like my engine is running when it's not. Help!
     
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