Injector/wiring ground problem? Mxs c15 cat 2006

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by OGARY88, Sep 20, 2017.

  1. OGARY88

    OGARY88 Bobtail Member

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    Sep 20, 2017
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    Here is the whole story with this money pit of an issue I am in. My truck can go 500 miles without messing up and the other times it can go 2 miles. The engine shakes uncontrollably the truck throws code 74. We replaced the injector still did the same thing and its all random when the problem occurs. We replaced all the harnesses more than once and checked all the grounds. We replaced the outer wiring harness for a 3rd time and the truck worked for 5 weeks. Now it is doing it again. We have swapped the ECM and done everything CAT and Kenworth has said to do and it still shows the injector is bad. Sometimes it will even show injector 1 is bad even after replacing. We have swapped out every injector / harness traced grounds and still no luck it will show the same problem.
     
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  3. dustinbrock

    dustinbrock Road Train Member

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    saskatoon,sk
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    Check the fuel pump on a dump or take it off and bench test it. DO NOT just test it at idle, anyone who says that's good enough is a moron.

    Change out the very very cheap pressure regulators. On my Sdp they are on the fuel filter housing.
     
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  4. Ace1428

    Ace1428 Bobtail Member

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    Jul 14, 2018
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    Did you ever get this problem fixed? I have one doing the same exact thing except code 72.
     
  5. DieselTech_Aus

    DieselTech_Aus Light Load Member

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    Dec 20, 2017
    WA
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    code 72 suggests you have an issue with cylinder 1 or 2. the return wires are all separate for each but the signal wires do 2 injectors each. the injector circuit is 120V and has some grunt.

    being code 72 I would suspect you have a wiring issue with the T858 grey wire on the external wiring harness or the front internal harness.

    it could also be the injector driver in the ECM which is often an early symptom exhibited prior to ECM failure
     
  6. Dakotafturner

    Dakotafturner Bobtail Member

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    Sep 14, 2018
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    Did anyone figure the problem? I have one doing the exact same thing
     
  7. Butch122

    Butch122 Bobtail Member

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    May 8, 2019
    San Juan Basin
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    Has anybody determined a solution to this problem? I have two trucks doing the exact same thing. Both are C15 Acert's and we've swapped injectors & injector harnesses multiple times. We've changed out vibration dampeners, installed new clutches and flywheels (to insure no additional vibration is wearing away on these)...basically everything that has been suggested could be the problem. Yet upon completion within a matter of hours or days the problem will resurface with broken ends on the injector harness or snapped off posts on the injector itself.
     
  8. Goodysnap

    Goodysnap Road Train Member

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    Jul 12, 2017
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    A certain attention to detail must be taken when replacing these UVC harness's. Over time yes the plastic on the connectors can get brittle but with age. I think you having an assembly issue. It takes time to check for clearance from moving components to make sure nothing is rubbing the harness.

    As for broken injector electrical studs, they are being over-torqued, plain and simple.

    When I do these I usually pull the base and replace all 3 harness's together to ensure a trouble free repair. Done correctly the harness's will last as long as the originals. Nothing else on the truck will cause premature failure IMO
     
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  9. pushbroom

    pushbroom Road Train Member

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    Only ever had 1 broken injector harness stud. Issue was too much torque. 22.13 ± 2.21 lb in is spec. I usually just install with a nut driver.
     
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  10. Goodysnap

    Goodysnap Road Train Member

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    With battery power cordless tools growing in popularity the air compressor runs less and less. This is one of many places they should never be used. Nut driver is my installation method as well. The urge to cheat for the sake of speed must be resisted.
     
    AModelCat, pushbroom and spsauerland Thank this.
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