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Dim Nighthawk low beams

Discussion in 'Western Plows Discussion' started by weshermanllc, Jan 1, 2012.

  1. weshermanllc

    weshermanllc Junior Member
    Messages: 12

    Ultramount, straight blade, 4 port iso, 2007 chevy.

    Plow side low beam headlamps not up power, thought I had a ground issue.
    Apparently have a power issue, after checking ground points, I pulled plugs from back of headlamps found 8.9v low beams and 14.1v high beams.

    Suggestions/help???
     
  2. Sharpcut 1

    Sharpcut 1 Senior Member
    Messages: 386

    I have seen this happen on a few Nighthawk lights. If you pull off the back cover, see if your plug is burnt at all. The ones that I have seen dim always had a loose connection at the plug on the bulb. Go to the auto parts store and get an H13 light end, cut out your old one, and splice it in. That's always cured the ones I've seen. Also, make sure wire is not rubbing at the thin metal bracket that holds the fixture on. Hope this helps, JOHN
     
  3. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,957

    where did you ck the voltage at? plow or truck?
     
  4. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    This has to be a problem on the positive side of the headlamp curcuit because both high and low beam share a common ground. The high beams work find and voltage there is good (so you say) so the ground must be OK. It could be a bad connection right at the plow plug, could be the headlight plug at the grill, could be the isolation module, the plugs into the isolation module or bad wiring.
     
  5. Sharpcut 1

    Sharpcut 1 Senior Member
    Messages: 386

    Read my above post. You are correct as far as being a power problem. The few I have seen have all been on the low beam power side. Ever notice how the plug still wiggles around even after black clip is engaged?? I think the connector is too loose and generating heat, hence the burn marks on the plug.
     
  6. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    Sharpcut I agree with what you said above being an issue he should check. I was just offering an alternative theory. I personally have never seen the burn marks on the headlamp bulb plug. And he never mentioned there were any burn marks. Now that I have heard your story about the loose connections I will look for it myself as I build & repair and add this issue to the long list of things that go wrong with Western plows. I agree absolutely that there is a bad, corroded or loose connection somewhere along the path but it could be anywhere. I recently repaired a similar problem on a truck where the fellows mounting bracket screws for the iso module had actually cracked the module and allowed water in which corroded the insides and the plug pins. There are multiple possibilites in this case and that is why people come to this web site. A person gets so many good answers from so many great people.
     
    Last edited: Jan 2, 2012
  7. weshermanllc

    weshermanllc Junior Member
    Messages: 12

    Back of the both side headlamps at the plug. While checking volatage at back of headlamp I found two different voltages (8.9v DS and 7.8v PS). After looking at the wiring schematic, I see that the DS low DS high DS common PS low PS high PS common all have individual wires back to plug #2 of the iso. So based on above I am suspecting the iso module.

    But none the less, today I have unplugged 28027-2 adapter and plugged plow harness directly into iso module, still have diminished headlamps. Returned adapter.
    I have checked both side lamp plugs, do not appear to be burned, corroded or discolored. Visual inspected grill plug, looks fine.

    Next I'm going to test iso module output at plug #2. Again after studying the wiring schematic I see I have to ground pin C of plug two to fool the iso into thinking the plow is connected in order to test output voltages. Thought I would have that done by now but just had an EMS run. So back to it.
     
    Last edited: Jan 2, 2012
  8. weshermanllc

    weshermanllc Junior Member
    Messages: 12

    "...I agree absolutely that there is a bad, corroded or loose connection somewhere along the path but it could be anywhere." Yeah these things are pull your hair out kind of problems, LOL "I recently repaired a similar problem on a truck where the fellows mounting bracket screws for the iso module had actually cracked the module and allowed water in which corroded the insides and the plug pins." Mounted with zip ties so don't have that problem, but it is mounted plugs up, going to change that when I get this figured out. "There are multiple possibilites in this case and that is why people come to this web site. A person gets so many good answers from so many great people." YOU ARE CORRECT SIR, and I spent hours searching and reading many other wiring problem posts before positing myself. I thank and appreciate all the help, Bill.
     
  9. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,957

    ok,,so i assume that your checking voltage at the plow lights. did you check the voltage coming out of the TRUCK headlights?? in and out?? yes it could be the iso...but if your truck is olny putting out 8.0v the iso is not going to up or dwn the voltage. now dont get me wrong there could be a problem in the iso dropping the voltage, but did you make sure you have a proper 12v going to the TRUCK headlights?
     
  10. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    Wow, reading your detailed description of voltage tests it is clear that you have an awsome grasp of electrical theory and schematic inturpratation. Good for you, I wish everyone could give such clear descriptions of what they are doing.

    I was just looking at the schematic myself and I am frustrated that I can't find a breakdown of the inside of the isolation module. As you said there are seperat wires from the iso mod to the grill plug and up to the lights for both sides, high and low beams. But what I want to know is where does the iso module get the power that is forwards on to the plow when the plow is hooked up. Does it just pass on the power that it takes from the truck lights or is truck light power just used to close relays which pass on fresh power. I have a sneeking suspition in the back of my head that plow headlight power is "fresh" power that is simply switched on and off by the signal from the truck lights. I suspect that plow light power may come through the 15A fuse near the iso module plugs. That being said, if there is only one power wire feeding the isolation module and multiple going out, each of which have different voltages, then the problem must be in the isolation module or the plugs.
     
  11. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    "the iso is not going to up or dwn the voltage." I dissagree with this statement. Any bad connection that has current flowing through it will produce a voltage drop. In electronics they call this an "I R drop" I being current and R being resistance. This can occur anywhere in the curcuit, including the isolation module. Since the power for headlights enters the iso module on one wire and exits through four wires and we are getting varrying voltage levels out, it may very well be the iso module. And, since it was mentioned that the iso module is mounted with the plugs pointing up this makes it that much more suspitious. At this point I am putting my money on isolation module or the plugs going into it.
     
  12. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,957

    hey mish,,if that was the case that the iso uses the "fresh" pwr,,then the high beams having correct voltage wouldnt apply.?
     
  13. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    sure would because the isolation module is getting one power source in (this good power for high beams) but the switches or plugs affecting the low beams are indipendant from the isolation module all the way out to the light fillaments. In fact there is a seperate wire right from the iso mod all the way out to each of the four fillaments. DS high & low, PS high & low.
     
  14. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,957

    ------not disagreeing with you one bit.......but if you dont have proper voltage going in your not gunna have proper coming out.
    i understand your gunna have volt drop. but "we" dont know what is going into the iso yet.
    "Since the power for headlights enters the iso module on one wire and exits through four wires and we are getting varrying voltage levels out, it may very well be the iso module"
    i thought that each light had its own input wire...pass and dr's...
     
  15. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    Quoted from the Western electrical maunual on page 13 http://library.westernplows.com/ddcommon/dd_pdf/pdfs/22373.07_110108_for_web.pdf
    With the park light circuit
    energized, the control circuit
    monitors the vehicle high
    and low beam inputs. When
    battery voltage is sensed, the
    appropriate solid state power
    devices are turned ON, supplying
    battery voltage to the snowplow
    headlamps via the vehicle and
    snowplow lighting harnesses.
    Toggling the dimmer switch
    between high and low beam will
    toggle the snowplow high and
    low beams.
     
  16. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    Since there is only one wire feeding all four plow headlight fillaments, and since he says it is only a problem with the low beam, the input voltage must be OK or the high beams would not be bright. This further reinforces the suspition of the isolation module or plugs coming out of it.
     
  17. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,957

    ok,,,so your still saying that the iso or plugs are the issue IF the iso is NOT using truck headlight pwr to pwr up the lights. the fresh pwr right???
     
  18. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,957

    BUT........it does not say WHAT pwr it uses to pwr up the headlights???
    i'm still thinking that it uses a "relay" type system inside it that uses truck voltage to power plow lights,,,,,like redirection.
     
  19. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,957

    no,,,he still hasnt said if the truck voltages are correct yet.
     
  20. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    He says above that he got two different (unacceptable) voltages on DS and PS low beams: 8.9 and 7.8Volts but hasn't even tested high beam voltage because they are bright is what I understand. But I am thinking that the fact that there are differences at all indicates that it must have multiple points of resistances on multiple wires. These variations in outputs could not be caused by a single fault on the input power source.

    And the truck voltages are irrelivent if they are only "triggering a solid state device" to switch fresh power on and off. I suspect that the truck headlights could be as low as 9 Volts and this would still be enough to switch the plow lights on. And when they did switch on the fresh power forwarded to the plow would burn bright regardless of the truck's shortcomings. I have seen this myself where people bring in old dim lighted trucks to find that a new iso mod plow has the nicest bright nighthawks. One customer said he was going to leave his plow on all year just so he could see at night. Joking of course but the point is clear.
     
    Last edited: Jan 2, 2012