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Western plow/Dodge truck lighting issue. Ideas??

Discussion in 'Western Plows Discussion' started by cubicinches, Nov 15, 2009.

  1. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412

    We've been going through all of our equipment, getting everything ready, and I've got an issue with my 2002 Dodge Ram 2500 with an 8.5' Western Pro Plus & 4 port isolation module system.

    The passenger side headlight on the truck is out when on low beam. When I switch to high beam, the drivers side works, and the passenger side goes out. When the plow is hooked up, it the does the same thing with the plow lights. I swithched the isolation module with a known good unit and no change. I unplugged the plow headlight harnesses, and plugged the original vehicle harnesses back into the truck headlights, and they work fine. I had an '05 Dodge with one truck headlight out last year, and it turned out to be the harness for that side. Is it possible that both of my harnesses are bad at the same time? Also, I checked the configuration plug for corrosion, etc., it all looks okay. This plow has been on this truck for 4-5 years, nothing has changed, so something has just failed.

    I'm fairly well versed with these systems, but I know there's some experts here, so just looking for some other ideas. Any input is appreciated. Thanks.
     
  2. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Sounds like it has a backed out pin on one of the lighting harness's. Disconnect the #2 harness at the Iso and check there for correct power and ground signals with a DVOM or test light while switching the lights (high & lows).
     
  3. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412

    Thanks for the reply. I assume you're referring to the plug in harnesses at the vehicle lights? If one or the other had a faulty pin, would it affect both sides... left and right?

    Also, checking for power & ground at #2 on the module... am I checking the module side?
     
  4. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    When checking start at #3 and #4 since their the ones coming into the Iso from the headlamps, you can disconnect those from the Iso and check the plug itself (not the Iso). If everything checks out with those then check #2 (back probe the plug with it still connected to the Iso) to be sure the signals are coming out of the Iso..which they probably are as the Iso's seldom die.

    If you check #3 and #4 right at the Iso (the harness's, not the Iso) and don't get what you should, then check those same two right at the truck lamps. It has to be getting lost somewhere.
     
  5. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412

    Very good. I was assuming I could backprobe #2 right at the grill connector. Like you said, I'm going to start at #3 and #4, I'll bet the problem is somewhere in those harnesses.

    Funny that I had this same problem last year with one side only on another Dodge, and it was the harness. I guess it just seems strange that it could be both harnesses at the same time. The truck does a lot of sitting in the off sesaon... plenty of time for things to corrode. :cry:

    Anyway, I'm going to check it out further tomorrow. I'll report back with my findings. Thank you for your input B&B!
     
  6. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    It's not uncommon for a single harness issue to affect both sides so don't necessarily assume you have an issue with both harness's. When they lose their connections they'll do some strange things. Especially on a positive common system.

    Keep us posted on what you find.
     
  7. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412

    Ahhh. I guess that's exactly what I was wondering. If the individual harnesses could affect one another. From your experience, it sounds like they can. I will definitely let you know what I find. Thanks again. :)
     
  8. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412

    Well... here's my update. Found my problem... actually problems.

    Both plug in harnesses bad!

    Checking left side, which had no low beam, at the iso module revealed no ground at the common in (dark blue)

    Checking the right side, which had no high beam, at the iso module revealed no power at the high beam in (dark green)

    Disconnected both harnesses, checked the culprit wires for continuity... dead. Then found the dreaded "green goo" on the outside of the black plug where the vehicle harness plugs into. This triggered my memeory on the issue I had last season with the '05 Dodge... the harness which failed on that truck had the same green crap around the wires on the outside of the connector. They aren't sealed very well where they enter the connector. The salty water from road spray probably makes it's way in there over time and eventually you've got green wires.

    Anyway, looks like I'm off to pick up a 26349 and a 26354 harness.

    Thanks again B&B, for your input on the issue. :waving:
     
  9. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Corrosion gets the best of everything. Good to hear your diagnostics found it. :waving:
     
  10. wideout

    wideout Senior Member
    from iowa
    Messages: 727

    I have a 2002 dodge 2500 that i had the same problem with. Check to see if your headlights are hb1 or hb5's you will find this on the front of the headlight. From the factory western sets up there wireing to work with the hb5's so in your wiring istructions it tells you that oyu need to change the wires around on oyur truck harness and it shows you how.l
     
  11. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412

    Actually, problem is all solved. Both plug in harnesses had corroded wires. This plow had been in service for 4 or 5 years without issue, so I knew something had failed. It wasn't the fault of something being configured incorrectly during installation. Thanks for the input though.
     
  12. wideout

    wideout Senior Member
    from iowa
    Messages: 727

    your welcome man! happy plowing!