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Problem with trailblazer 325 diesel

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  • Problem with trailblazer 325 diesel

    Hi, first time Miller owner and first post here on the forum. I recently bought a 2018 Trailblazer 325 diesel with 2700 hours on it. Other than the LED numbers not displaying completely, the machine works flawlessly for around 2 hours but then starts cycling between low and high idle, can’t change the weld type knob, can’t adjust the power knob, and no weld output. Generator works fine though. If I let the machine cool down everything goes back to normal again. I’ve done complete maintenance and changed the slip brushes. The fuses are good. Any idea what the problem could be?
    Last edited by PanaWelder; 10-02-2021, 02:02 PM.

  • #2
    Just an update. I ran the welder all day today. After around 2 hours it started cycling between low and high idle again, as though the machine thought there were amps being drawn. The amp setting would jump up and down together with the changing idle speed. The two knobs became unresponsive again, however this time I could continue welding. I just couldn’t change the settings. After welding like this for around 30 minutes, the machine came back to normal and I could change the settings again. So, I guess the heat isn’t an issue. Although it does only start happening after around 2 hours of use. I’m happy I could weld today, but something is definitely weird. If anyone has experience or ideas please let me know. Thanks
    Last edited by PanaWelder; 10-03-2021, 04:17 PM.


    • #3
      The display board has multiple uses. Obviously amps and volts and idle. Best guess because your display isn't working properly is that is your problem.
      You would have to check voltages from the regulator board to be sure. If it welds, the IGBT board is working.
      Could be as simple as a LEM as I've seen them do crazy things. If you can live with it until it finally quits then take it in and have someone do a complete diagnostics instead of just ordering parts.


      • #4
        Thanks for the reply. I live in Panamá and there isn’t any competent shop that will diagnose it for me. They’ll just want to replace the whole service control board that is $1500 here and hope for the best. Since the display is on the service control board and it’s not working properly, I might actually need a new service control board. But any ideas if it could be something else?

        I’ve been welding the last few days and the problem has become totally random. Never know when it’ll act up….but so far it keeps going away. As long as it’s like this, I can live with it.

        If I do need to install a service control board, I prefer to order and install myself. Just want to try everything I can before spending the $1000 plus for the part