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02 Ram 2500 Lighting question

Discussion in 'Fisher Engineering Discussion' started by Musictoo, Jan 7, 2012.

  1. Musictoo

    Musictoo Junior Member
    Messages: 18

    Just picked this truck up used. Minute Mount plow. Had it for 2 months and last night looked out and saw the plow parking lights on. Checked the headlight switch an it was off. I can hear the relay in the isolation module click when I disconnect the lighting plug and the lamps go out. It has a 26400 isolation module. Not sure where I should start looking, bad ground, bad module?
     
  2. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,966

    so this was the first time you had the plow hooked up??
    did the plow come with the truck??
    does it do it all the time?
     
  3. Musictoo

    Musictoo Junior Member
    Messages: 18

    Plow was hooked up when I got the truck, has not been removed. Everything worked properly prior to this. The last time I moved the truck was a week ago.
     
  4. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,031

    Either you have something going on with the truck, or the ISO is junk.
     
  5. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,966

    so its been hooked up ever since you got it,,,then all of a sudden the lights come on??
    has it ever happened before this?
     
  6. Musictoo

    Musictoo Junior Member
    Messages: 18

    Everything was hooked up and working when I got the truck. The truck lights work properly when the harness is disconnected, and the plow lights work properly when they're connected. Light switch off, plow markers stay on. The truck hadn't been moved for a week when this started.
     
  7. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,966

    and its just the plow lights,,not your truck lights??
    but it cant be,,your plow and truck parking lights are wired together....either, like was said above iso or theres a wiring issue,,,wrong pwr wire hooked up somewhere
     
  8. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,031

    The park lights aren't directly supplied via a...pass through in the ISO (so to speak), rather through a series of relays within the ISO. Hence the 12v lead from the Motor Relay which supplies power to both sides of the ISO (control & lights). Where Musictoo has mentioned that the truck's lights work poperly without the plows electrical system connected, then the only other player would be the the 12v coming in from the solenoid, which is bleeding through an internal relay and activating the park lights on the plow. So, in short, my take on it is that the ISO has gone bad.


    Taken from the "Theory of Operation":

     
  9. Musictoo

    Musictoo Junior Member
    Messages: 18

    I removed the left headlamp assy and when I disconnected the headlamp jumper the relay clicked open and the lights went out. Removed the connecter from the headlamp bulb and that made no difference. As soon as you plug the plow bypass into the headlamp bulb connecter the relay clicks on and the plow park lights go on. This is all with the headlamp switch off and the ignition key off.
     
  10. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,031

    Yes, because it is triggering the relay switch in the ISO....it completes the circuit. The lights...or should I say headlamps themselves play no part in the operation. The park light side controls which direction the headlamps power goes (truck side or plow side). The clicking that you are hearing is the headlamp relay(s) within the ISO trying to supply power to the plows headlamps, except it can't execute this due to the lack of power being supplied from the trucks headlamps (the switch is off).

    With the plow plugged in, remove the red / green wire from the motor relay (or simply remove the 15amp fuse)...the same will occur; the park lamps on the plow will go out....unfortunetly this is true even on a working system, so it doesn't prove much.
     
  11. Musictoo

    Musictoo Junior Member
    Messages: 18

    So does this mean that the iso module is bad?
     
  12. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,031

  13. Musictoo

    Musictoo Junior Member
    Messages: 18

    Awesome lol
     
  14. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,031

    You can still use it, just remove the fuse after use so you won't drain your battery (located on the #1 harness, just off the ISO *15 amp). By the sounds of it, this isn't your daily driver anyway.
     
  15. Musictoo

    Musictoo Junior Member
    Messages: 18

    I was just going to unplug the harness disconnect, any reason not to? I may get an iso anyway, after all the mucking around the left plow headlamp won't come on now...
     
  16. Musictoo

    Musictoo Junior Member
    Messages: 18

    And thanks for all your help Ryan, I really appreciate it.
     
  17. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,031

    That works too. Headlamp is most likely unrelated to the iso....check your connection to make sure.
     
  18. Musictoo

    Musictoo Junior Member
    Messages: 18

    Checked the connection. Truck lamp works when plow is disconnected. Brand new headlamp. Weird.
     
  19. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,031

    ISO taking a turn for the worse then, it's probably the board itself that is fried.

    After thought to be thorough....You did check the truck to fisher harness as well as the bulb socket end right.?.?
     
  20. Musictoo

    Musictoo Junior Member
    Messages: 18

    I did. The harness looks good, the disconnect has a little crud in it, not too bad though. I'm thinking iso still...