# Plow light problems



## Plugger49 (Jan 12, 2017)

Hello all,new to forum. I've been plowing for over fifty years,and not ready to retire. I'm hoping someone can be of help. I hit a really BAD manhole and blew the hell out of my original Grote plow lights. I bought a set of Peterson Blade Lites,and having difficulty hooking them up. Issues; my harness has six wires,the Petersons have five. Five,makes sense-high beam,low beam,parking,directional and ground. I have the low beam functioning,the rest is a puzzle. I had the left directional working,then it's not. Same thing with the high beam and parking. Petersons came with a paper showing which wire is for what,so that's not the problem. I think the problem is on the truck side. Here's the thing- I bought this truck('03 GMC 3500,1-ton dump),just recently. I knew I had plow lites,BUT, I never actually checked what else was working. ( I know- at my age,you'd think I'd know better). Over the years I've had just about every problem with plow trucks,including light issues. I'm not familiar with Fisher MM 2 plow wiring. Does anyone have an idea where to start? Thanks for any help.


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## Randall Ave (Oct 29, 2014)

I think Fisher runs two grounds out. Do your connections inside the headlamp. Just use a test light for the original functions. Wire up accordingly. Go to Fisher site for diagram if needed. And use heat shrink connections.


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## dieselss (Jan 3, 2008)

What lights do you have on the plow now.?


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## Plugger49 (Jan 12, 2017)

Thanks for your help. I know the Black/Orange is a ground, it was secured inside the light via eye connector with screw, and a slightly thicker gauge. I'll try to figure out what(or if?),the other one is. Also- I don't know what an isolation module is,does,or even looks like. I used a tester on the truck side plug. It seems there's no juice coming out. I brought up the diagrams,their seems to be only that one ground(bulk/org),but I can't imagine what a sixth wire's function would be,so you may have a point.I'd hate to have to rewire this. I may have to get through the season with just the low beams. I'm the lead truck in a six gang group,so directionals are a plus. I have to do this work outside,and the Boston weather can be harsh.


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## Plugger49 (Jan 12, 2017)

dieselss said:


> What lights do you have on the plow now.?


As mentioned- I destroyed my original lights,and trying to put Peterson's on. The diagram for their lights,is clear on what the five wire's functions are. Of course the colors don't match up. I've rewired dozens of trucks, so I have a pretty good idea what I need to do. But, I do not know these new MM systems. Thanks for your input.


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## dieselss (Jan 3, 2008)

Were the old ones the black plastic rectangular ones?
Or the 2 stud big ones?


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## dieselss (Jan 3, 2008)

Or how many plugs at the grill for the plow


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## leolkfrm (Mar 11, 2010)

use a battery charger or battery and pin out the new lights...,
then pin out the harness at the truck and make a wiring diagram as you go..
only way i know without diagrams for both

dont want to admit but i find myself writing stuff down so as i do it i can reconfirm it


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## Plugger49 (Jan 12, 2017)

dieselss said:


> Were the old ones the black plastic rectangular ones?
> Or the 2 stud big ones?


Old rectangular-one stud.


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## Plugger49 (Jan 12, 2017)

dieselss said:


> Or how many plugs at the grill for the plow


It's a three plug, eleven pin.


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## Plugger49 (Jan 12, 2017)

leolkfrm said:


> use a battery charger or battery and pin out the new lights...,
> then pin out the harness at the truck and make a wiring diagram as you go..
> only way i know without diagrams for both
> 
> dont want to admit but i find myself writing stuff down so as i do it i can reconfirm it


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## Plugger49 (Jan 12, 2017)

Yes, I always make a diagram and now(with these fancy phones),I take a photo. My mind's not getting any sharper. Thanks


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## Plugger49 (Jan 12, 2017)

Plugger49 said:


> Yes, I always make a diagram and now(with these fancy phones),I take a photo. My mind's not getting any sharper. Thanks


The problem is on the truck side,the new(Petersons) are fine,I've already checked them. I either have a line break,or its this isolator module (that I've read of), or there's a fuse-relay,etc.problem. I was hoping someone experienced this problem. Like I mentioned,I really don't want to do an entire rewiring. And,I still haven't figured out why there's six wires on the truck side harness....? There's nothing more frustrating than a wire problem.


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## Randall Ave (Oct 29, 2014)

Let's see, park, turn, ground, high, low, ground. That's six. The new ones run the headlamp ground separately.


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## dieselss (Jan 3, 2008)

Are you looking at the wires inside the light or going to the light?


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## Plugger49 (Jan 12, 2017)

Randall Ave said:


> Let's see, park, turn, ground, high, low, ground. That's six. The new ones run the headlamp ground separately.


You listed ground twice,not sure where,or how to ground the second one. The new ones come with one ground. Again,the issue is NOT the new Peterson Blade Lites. I'm not getting power from the truck side connection,on all but the low beam,and I have no idea why. I'm not clear on what you mean by- the new ones run the headlamp ground separately. There are five wires with the Petersons, one being a ground,which I connected to the black/orange ground wire from truck side harness. The Petersons Do Not have two ground wires.


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## Plugger49 (Jan 12, 2017)

dieselss said:


> Are you looking at the wires inside the light or going to the light?


The wires inside the new Peterson lights are Fine. They are not the issue.


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## kimber750 (Sep 19, 2011)

Plugger49 said:


> You listed ground twice,not sure where,or how to ground the second one. The new ones come with one ground. Again,the issue is NOT the new Peterson Blade Lites. I'm not getting power from the truck side connection,on all but the low beam,and I have no idea why. I'm not clear on what you mean by- the new ones run the headlamp ground separately. There are five wires with the Petersons, one being a ground,which I connected to the black/orange ground wire from truck side harness. The Petersons Do Not have two ground wires.


Instead of the blk/org wire use blu/org on passenger side and lt blue driver side. Those are the grounds for headlight from module.


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## kimber750 (Sep 19, 2011)

Plugger49 said:


> Thanks for your help. I know the Black/Orange is a ground, it was secured inside the light via eye connector with screw, and a slightly thicker gauge. I'll try to figure out what(or if?),the other one is. Also- I don't know what an isolation module is,does,or even looks like. I used a tester on the truck side plug. It seems there's no juice coming out. I brought up the diagrams,their seems to be only that one ground(bulk/org),but I can't imagine what a sixth wire's function would be,so you may have a point.I'd hate to have to rewire this. I may have to get through the season with just the low beams. I'm the lead truck in a six gang group,so directionals are a plus. I have to do this work outside,and the Boston weather can be harsh.


Won't be any juice unless the plow side plug is plugged in. It has a jumper in the harness to activate lights.


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## Randall Ave (Oct 29, 2014)

Plugger49 said:


> You listed ground twice,not sure where,or how to ground the second one. The new ones come with one ground. Again,the issue is NOT the new Peterson Blade Lites. I'm not getting power from the truck side connection,on all but the low beam,and I have no idea why. I'm not clear on what you mean by- the new ones run the headlamp ground separately. There are five wires with the Petersons, one being a ground,which I connected to the black/orange ground wire from truck side harness. The Petersons Do Not have two ground wires.


I didn't design it. But it is wired as these guys have said.


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## Plugger49 (Jan 12, 2017)

Thanks fellas. I'll try what you said with the grounds. It's going to be a lot colder here(Boston area),inthe next few days though. We're having a winter like last year- when there's percipertation in the air,the temperature goes up,so it can rain,then it goes to balls freezing temps with zero moisture in the air. Very aggravating at the least,it shouldn't rain in New England in January-Wha Wha


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## Plugger49 (Jan 12, 2017)

Also-kimber, I'll do what you said with the ground wires, and I guess I'll ground the thicker bulk/org ground to the stud/frame area. But I don't see how these grounds are going to change the fact that there's no power (mostly) coming from truck side....?


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## Randall Ave (Oct 29, 2014)

If you have no power from the truck side. You have to check for power in, and power out at the module. When the plow harness is connected to the truck it completes a ground and power circuit that switches the head lamps over. With a wiring diagram not that bad to check.


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## kimber750 (Sep 19, 2011)

Plugger49 said:


> Also-kimber, I'll do what you said with the ground wires, and I guess I'll ground the thicker bulk/org ground to the stud/frame area. But I don't see how these grounds are going to change the fact that there's no power (mostly) coming from truck side....?


If you are testing for power without plow harness plugged in the module is not switching lights over to plow. Only thing that will have power in truck side plug would be park lights.


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## Plugger49 (Jan 12, 2017)

Ok,thank you both. It's 18deg. this morning,I'll wait for a little warm up.


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## Plugger49 (Jan 12, 2017)

I don't know where to find said module,or what it even looks like. The diagrams I'm seeing do not mention the word module.


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## dieselss (Jan 3, 2008)

http://library.westernplows.com/doc...ename=22373.07_110108_for_web.pdf&doctype=pdf

Here's the diagrams for all the systems.


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## Plugger49 (Jan 12, 2017)

Thanks dieslss, your not going to believe it BUT- I still don't know what this module looks like,or exactly where it is located.


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## dieselss (Jan 3, 2008)

It's a rectangular box with 3 or 4 medium sized plugs going to it.....


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## kimber750 (Sep 19, 2011)

One of these two.


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## Randall Ave (Oct 29, 2014)

I read this again. Unless I missed it, he never stated if he has two or three plugs at the plow. Maby a very old relay system.


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## kimber750 (Sep 19, 2011)

Plugger49 said:


> It's a three plug, eleven pin.





Randall Ave said:


> I read this again. Unless I missed it, he never stated if he has two or three plugs at the plow. Maby a very old relay system.


Thumbs Up


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## Plugger49 (Jan 12, 2017)

I located the module,I do hope that's not the problem. Their $160,so I'll check everything else first. My father always said"start with the easy and work your way to the hard",it was always good advice.


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