# Fisher MM1 wiring/solenoid



## stallion81 (Feb 5, 2014)

Hey guys new to board, 1st plow I owned. Plowin for my brother since 96' so Ive worked on a few a bit, but not wiring. I've only got 20-25 hours on it as I was down early year rebuilding my truck engine. I did do general maintenance as in replacing ATF with Blue, cleaned filter,housing and magnet, dielectric plugs.

Fisher MM1, stoped working yesterday on a push. Just a click from motor solenoid. Up a bank, chain up and took it home. Grabbed a solenoid, they gave me an Oregon 33-431 universal. I checked the motor, runs on jump. So I put the new solenoid in, now not even a click. 

Now this is not wired per say fishers diagrams. Only the brown/red to the primary, other primary(ground), they had running directly to control(black/orange from control was cut and never mounted to solenoid).My truck does have a toggle for the lights, but its backwards as the plow lights work with truck switch, I hit the toggle for the truck lights. All lights work, so I'm assuming my issues are just with the one harness lead(plow motor). It is a 3 plug MM1. My test light housing is broke, works but the lead is short so I'm gonna get a new one today. 

I'll check all the motor hook ups today, and the ground curcuit from the motor, but I guess I would have to ask if the universal solenoid needs a ground from a primary, or if it grounds thru the mount? My old solenoid kinda looks like an old Ford solenoid.It must have grounded thru the mount as only 1 primary had a wire. It did and does have 12v at the brown/red primary wire. Thanks for any help.


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## dieselss (Jan 3, 2008)

Yea if the solenoid has 4 terminals it needs to be grounded. 2 big terminals are your pwr in and pwr out. The 2 small. One is signal pwr and one is gnd


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## unhcp (Jan 20, 2010)

that solenoid should work according to the images i saw online


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## stallion81 (Feb 5, 2014)

Thanks Ill try a ground wire....However I have to assume not all 4 post solenoids need a ground from the primary. Looking at the old one, it must indeed be a truck starter solenoid. It does have the I & S on the primaries. If I remember correctly that was ignition and starter? I thought those were grounded thru the mount? The old one I pulled didn't even have a nut on the "I" bolt. No wires were connected to it. Just the 12v brown/red hooked to the "S" post coming from the control. Granted its been over 10 years since I owned an old CJ or F-250.

I got a new test light, gonna start checking it. I'll assume its wired for a body mount "grounded" solenoid, and I have a new style. I cant recheck the old one as 1 of the "battery posts" snapped off on removal. Hope a ground wire from the other primary post is the trick and the old solenoid was indeed bad.


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## dieselss (Jan 3, 2008)

Without seeing it you could be right. Just get a plow solenoid, or one rated for plowing and you'll be fine


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## stallion81 (Feb 5, 2014)

YEAH BUDDY....Your the man, dieselss. Quick ground from the other post to the battery.....all good. Thanks for the help. My solenoid exp is with 78-79 Jeep CJ's and 77-79 F-250's. Those were indeed grounded thru the mount as was the old solenoid for the plow. In fact I bet it was a Ford starter solenoid.

Thanks again.


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## dieselss (Jan 3, 2008)

Your prob right it was a ford solenoid. Good deal glad its fixed. Happy plowing


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