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MD 75 Lighting Problem

Discussion in 'SnowDogg Snow Plows' started by blue22580, Nov 27, 2012.

  1. blue22580

    blue22580 Junior Member
    Messages: 14

    The left headlight doesn't switch over to the plow side...left headlight on truck is on but the plow side light is not on. It is only the left side that is experiencing this problem. The right plow side light is on and the right headlight of the truck is off as it should be. The same issue exists with the high beams. Turn signals are working properly.

    Any suggestions? Thanks in advance.
  2. plowguy43

    plowguy43 PlowSite Fanatic
    Messages: 5,281

    Check all connections between the plow lights to the relays. could possibly have a ground issue
  3. smoorman

    smoorman Sponsor
    Messages: 447

    Sorry for the delay. Are both the high and low beams not switching over? Or is it just low beam?

    In case like this, a wiggle test is always a good idea - you've got either a bad relay, or a bad connection somewhere. If it's both high and low, then it's probably not a bad relay.

    By bad relay, I don't necessarily mean the relay itself is bad, it could just be bad contact between one of the relay pins and sockets.
  4. blue22580

    blue22580 Junior Member
    Messages: 14

    The high beam is not switching over either.
  5. smoorman

    smoorman Sponsor
    Messages: 447

    Sorry, you said that in your original post.

    That's pretty strange - the only thing that should prevent the lights from switching over is the relays - and it sounds like you've got 2 that aren't shifting. If the truck lights are staying on, then the problem is not likely to be the connectors (corrosion, etc.)

    Relays - looking down at the relay box with the cover remove - harnesses point towards you.
    (HB - High, LB - low, A - short side, B - long side)


    With the truck off (so you don't short anything) - remove the HB and LB relays from the side that you're having trouble with and swap them with the other HB and LB relays. See if the problem moves. Very unusual to have 2 bad relays (or 1 even) - but they are inexpensive parts.

    While you're at it check for corrosion - if one side of the relay box is more exposed than the other I suppose that could happen.
  6. blue22580

    blue22580 Junior Member
    Messages: 14

    Sorry I'm a little late here and thank you for the responses. I took it to the dealer who installed it and it ended up being a bad relay.
  7. hedhunter9

    hedhunter9 Senior Member
    Messages: 212

    I am seeing lots of problems with this light relay box. It is a very
    poor design. To put it out front like that and exposed to the elements
    is just poor planning.
    Buyer should put it inside the cab away from the elements or have a better sealed box for the relays..
    I have 2 MD75 and both have corroded relay sockets that even with new relays, the lights don't work. Have tried baking soda, electric cleaner, battery cleaner,
    The only way to get the low beam light to work, is to wedge something between the relays, then it will stay on.. Sure not what we should have to do.
    I have taken an inner tube, cut a length of it and put the relay box in it with the ends zip tied shut. Just to protect it from the elements..
    Not something I should have to do...
    Wish SnowDogg would do something better...
  8. 04ram1500

    04ram1500 Member
    Messages: 97

    My last truck had the relay box right in the front grill. I had to take all the relays out and clean it every summer, then pack it full of dielectric grease.

    My new truck the box was placed next to the underhood fuse panel, it doesn't seem to get wet anymore. Whether this was a design change by snowdogg or by my dealer I don't know. I am hoping I don't have to take it apart every year anymore. Only time will tell
  9. Unrealo4

    Unrealo4 Junior Member
    Messages: 14

    Mine is by the firewall in my truck. I installed it and have had zero issues with it in 3 years. I have not even opened it for greasing. The installer determines where it goes not buyers.
  10. smoorman

    smoorman Sponsor
    Messages: 447

    Bingo - installation is key to any plow. There are a lot of "unsealed" components under your hood - but not by the grill or in your wheel well.