detroit 14l skip, never seen this before, need advice!

Discussion in 'Freightliner Forum' started by Prohemi500, Feb 9, 2015.

  1. Prohemi500

    Prohemi500 Bobtail Member

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    Jul 4, 2013
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    I will try to make this as short as possible. I have never seen this problem before. 2006 Columbia with a Detroit 14l. I was coming home empty the other day traveling thru the rain. I pulled up to fuel and the truck would not shut off with the key! I searched the forums here and found someone who had the same problem... Water leaking into the B pillar behind the drivers seat and right onto the pdm! (I think that's the pdm with fuses, please correct me if I'm wrong) I dried it off best I could and left the panel door open so that the water could no longer touch it and it would be exposed to the heater in the cabin which would help it dry.. Later in the day the switch began to work again and everything seemed fine. As I arrived home from the long trip I began to notice that the truck had a skip. Under wide open throttle it just coughs and sputters and the boost gauge is going to zero and back up to full boost very quickly. Shift gears, and run WOT and it may run clean and normal thru the next gear or it may stumble again. It seems 10th (10 Spd) is the worst. It's very unpredictable, but it seems to stumble less noticeably under 50% throttle or less. Engine has all deletes for egr, vpod, it has a standard (non vnt) turbo etc.. No codes but when driving the truck down the road with a computer monitoring the engine, the engine load at WOT will be 100%, and when the stumble starts, the engine load will go to 0% and right back to 100% when it quits. This all happens very quickly! Freightliner man says he has never seen this before. The TPS also reads 100% when at WOT and never falters. The only thing I know to do at this point is to start throwing parts at it. I am going to start with the PDM since this problem seemed to start after it got wet. Then cam and crank sensors and a injector harness will be in line afterwards if the pdm doesn't fix it. Next I plan to start with a fuel pump although it doesn't act like its fuel related to me. The truck already has a brand new fuel regulator on the back of the head, engine harness to ECM and ECM to firewall harness so that is not the problem. I have also tried another ECM, and that is not the culprit neither. Any ideas will be greatly appreciated!
     
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  3. Old Man

    Old Man Road Train Member

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    With it not shutting off with the key tells me a relay is stuck. When you turn the key a relay closes that send power to the gauges, ac fan , engine etc. Water will screw it up, find it and change it first.

    The wet relay may not let full power thru which can cause your other problems.
     
  4. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

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    check upper rear driver side of cab for old qualcomm wiring left over from previous owner.units get removed when not needed,but wiring stays.wiring still tied into datalink.if you have wiring still there,climb up back of cab and look in connector.gonna have green corrosion inside.quick fix is to cut connector off.proper fix is to remove all old wiring.good luck.p.s.also change aux pdm,cheap insurance if you do not know if it has been changed yet.20 minute job.
     
  5. Andre_K

    Andre_K Bobtail Member

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    May 3, 2016
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    Wow. You’re absolutely right, about the old Qualcomm harness! I had the same exact problem, where truck wouldn’t shut off with the key, and left side of dash gages not working with key on. I’ve been bobtailing and pulling chassis in winter slush. Sure enough: Qualcomm plug on the outside of bunk had corrosion inside. As soon as I cut it off, truck shut off! All gages started working, when stated the truck! Will remove the old harness completely, next.
    Thank you so much for the tip!!
     
  6. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

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    No problem. One of the benefits of working on all makes and models is getting to experience everything.
     
  7. 972002

    972002 Bobtail Member

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    Feb 6, 2018
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    Look at the above video and tell me if this is what you are experiencing.
     
  8. 972002

    972002 Bobtail Member

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    Feb 6, 2018
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    Can you tell me if this is what you are speaking of?
     
  9. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

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    Yes. Those are the symptoms. Follow the steps that I outlined in previous post.
     
  10. nighthawk solutions

    nighthawk solutions Bobtail Member

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    Aug 25, 2021
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    Do I jus cut wire off if soo where at
     

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  11. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

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    Properly remove the whole wiring harness inside and outside the truck. Cutting that harness is an emergency, get out of trouble solution.
     
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