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What to do? "Unknown Diagnostic" code with Series 60 Detroit Diesels.

Discussion in 'Engines' started by av8tor69r, Jan 23, 2022.

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  1. av8tor69r, Jan 23, 2022
    #1
    av8tor69r

    av8tor69r New Member

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    I have twin 825 hp MTUs (Series 60 Detroit Diesels) in a 59 Marquis (Carver). Engine performance has been very strong.

    After some minor electrical work (replaced a couple of non-engine related AC breakers on the electrical panel), I started both engines. The STBD side engine started as usual with no alarm; the PORT side engine started as usual, but a Check Engine alarm went off with an "Unknown Diagnostic" code. No flash code. (See Attached)

    In an attempt to troubleshoot, I turned off breakers and power to the PORT engine and let sit for 15 minutes then returned power and restarted. Both engines started right up as usual, but the Check Engine alarm returned on the PORT engine. I silenced the alarm and idled around the marina a bit. Both engines ran perfectly with all temps and pressures identical and within the proper range. Very frustrating.

    I have read comments from very experienced Detroit Diesel mechanics related to situations like this who indicate that instead of throwing parts at the engine in a shotgun approach to try to solve the problem, the alarm should simply reset and have the user continue as usual, continuing to monitor performance very closely.

    Has anyone else experienced this with these engines? What do you recommend? Any help appreciated.

    Attached Files:

  2. Capt Ralph, Jan 23, 2022
    #2
    Capt Ralph

    Capt Ralph Senior Member

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    Lets talk about what minor electrical work you did.
    WHAT DID YOU DO EXACTLY?
    Any sparks?
  3. av8tor69r, Jan 23, 2022
    #3
    av8tor69r

    av8tor69r New Member

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    Hi Capt Ralph, I was running an electrical heater that tripped an A/C breaker to the saloon area receptacles. Yes, when I tried to reset the breaker, it did spark. Concerned that the breaker was faulty, I had a marine electrician replace it with a new 15 amp breaker. All working just fine after replacement. Do you think the sparking had something to do with the Check Engine alarm?
  4. Capt Ralph, Jan 23, 2022
    #4
    Capt Ralph

    Capt Ralph Senior Member

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    I'm reading the electrical work, was on the ACv panel and not the DCv panel?
    And just the ACv breaker was replaced.
    Correct?
    The battery charger is on and all the batteries are fully charged with no issues?
  5. av8tor69r, Jan 23, 2022
    #5
    av8tor69r

    av8tor69r New Member

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    Correct. Just the AC breaker was replaced not anything on the DC panel. I did NOT think to check the charge on the batteries...
  6. Capt Ralph, Jan 24, 2022
    #6
    Capt Ralph

    Capt Ralph Senior Member

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    Next two thoughts;
    Get a DDEC/MTU tech out there with his laptop.
    1) Read the codes and raw data and submit that to MTU support.
    2) Ensure you have the latest software in your equipment.

    Past that, watch the vitals and run them..
  7. av8tor69r, Jan 24, 2022
    #7
    av8tor69r

    av8tor69r New Member

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    Sounds like a good plan. Thanks so much for the help!
  8. DOCKMASTER, Jan 24, 2022
    #8
    DOCKMASTER

    DOCKMASTER Senior Member

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    Have you ever used McConnel Marine in your area? They are a Detroit/MTU Specialist. I had them do some work on my Detroit Diesels when I bought my boat in Newport. That was 10 years ago now so you would need to verify they are still around. He was very good and quite reasonable. If memory serves, he used to be a DD Factory Tech.
  9. Pascal, Jan 24, 2022
    #9
    Pascal

    Pascal Senior Member

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    unknown faults can sometimes be caused by voltage issues. How did the engines sound while cranking? Did port crank slower?

    another possible cause would be the small battery in the engine computer. Had the issue on one of 16V2000s a few months ago although the error was “battery capacity exhausted”. Engine ran fine too
  10. av8tor69r, Jan 24, 2022
    #10
    av8tor69r

    av8tor69r New Member

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    I have not used McConnel. I'll look them up and give them a try. Appreciate the lead.
  11. av8tor69r, Jan 24, 2022
    #11
    av8tor69r

    av8tor69r New Member

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    Both engines started right up, immediately, seemed like half a crank... ran smoothly. I've learned from Capt Ralph about the connection between potential unknown codes and voltage issues.
  12. DOCKMASTER, Jan 24, 2022
    #12
    DOCKMASTER

    DOCKMASTER Senior Member

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    McConnell Marine. # is... Nine zero nine- seven nine four - 2288.
    Bruce McConnell is his name.
    Last edited by a moderator: Jan 24, 2022
  13. Bpro, Jan 3, 2023
    #13
    Bpro

    Bpro New Member

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    Year old post but what was the outcome? Did you get the issue resolved?
  14. Hpozzuoli, Jan 4, 2023
    #14
    Hpozzuoli

    Hpozzuoli New Member

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    I didn’t realize series 60’s were marinized. I had a series 60 in my last RV. It is the ultimate RV engine for its dependability and power. The new RV is a little smaller and Cummins powered.
  15. Capt Ralph, Jan 4, 2023
    #15
    Capt Ralph

    Capt Ralph Senior Member

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    The Detroit Series 60 has claimed global fame.
    Had some ancillary issues when first marinized. But when those hang on bracket issues were resolved, It became a global marine engine.
    MTU marketed it with the DDEC and improved exhaust manifolds and it became my most favorite marine engine.
    Sadly, on my budget, I just light serviced and changed the oil on them for other very proud owners.

    I remain still chest beating and proud of my 44 year old mechanical Series 71.

    DDEC had some hick-ups. In a boat, low voltage is usally the #1 issue.
    Low batteries, bad cable connections and green in the wires.

    I think Lucas had something to do with these issues???? :rolleyes::rolleyes:
  16. GPO, Jan 9, 2023
    #16
    GPO

    GPO Member

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    I think Lucas had something to do with these issues????

    Lucas Electrics...in the automotive world the jokes are numerous, including "Lucas, Prince of Darkness" and "Lucas is an acronym for Loose Unsoldered Connections And Splices".
  17. Capt Ralph, Jan 9, 2023
    #17
    Capt Ralph

    Capt Ralph Senior Member

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    Yep
    Also famous for smoke leaking out of their equipment.
    I remember somewhere a special can of Lucas Smoke you could re-inject back to the wires.
  18. chesapeake46, Jan 11, 2023
    #18
    chesapeake46

    chesapeake46 Senior Member

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    That canned smoke does not work as well as you think tho.
  19. Capt Ralph, Jan 12, 2023
    #19
    Capt Ralph

    Capt Ralph Senior Member

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    Naw, I always preferred fresh factory wire and components with factory installed smoke.
    Not rebuilt with second-hand smoke from China.
  20. Capt Ralph, Jan 12, 2023
    #20
    Capt Ralph

    Capt Ralph Senior Member

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    I'm still amazed anybody else still knows of Lucas.
    Kids and mid aged folks don't have a clue.
    Most of who I knew,, who worked on the stuff is gone. :(
    alvareza likes this.
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