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Trouble with wireing

Discussion in 'Fisher Engineering Discussion' started by gmcsierra1500, Oct 28, 2006.

  1. gmcsierra1500

    gmcsierra1500 Senior Member
    from CT
    Messages: 151

    Im looking at buying a used MM2 plow, most of the ones I find dont have the right wireing and mount for my truck, What im having trouble with is understanding this difference between the 3 port isolation modual, and the 4 port, and which one I need, also do soem MM2 plows have 2 plug systems or all they all 3? whats the difference? I have a 2000 GMC Sierra 1500, Any help is appreciated.
  2. rtm038

    rtm038 Senior Member
    from NJ
    Messages: 231

    The 3-port module is the newest version Fisher is using, while the 4-port is the original isolation module design released a few years ago. Since the 3-port was just released this season, or maybe last season, most of the used MM2s out there are going to use the 4-port system. As for plugs, the Minute Mounts that used the older style SEHP (looks like the old Western/Fisher cable operated pumps, but feature solenoid valves mounted to the body) pumps used the 2-plug set-up. The 3-plug set-up came out with the introduction of the E-Force Isolation Module harnesses and Insta-Act pumps.

    If you call your local dealer, they will be able to give you part numbers for the exact wire harnesses and isolation module your truck needs. Or keep an eye on Ebay. There are usually quite a few Fisher MM2s, vehicle wiring, mounts, etc. up for auction. In fact, there always seems to be more items for GM trucks than any other brand.