It's always at the worst possible moment that your Fisher plow will not go down, usually right in the middle of a heavy storm when the snow is piling up and you've got a long list of driveways to clear. You hit the button on the controller, you might hear a click or a hum, but that blade stays stubbornly stuck in the air. It's enough to make you want to throw a wrench across the garage, but before you get too frustrated, know that this is a pretty common issue with a few likely culprits.
Usually, when a Fisher plow refuses to lower, it's either an electrical hiccup, a hydraulic valve that's acting up, or a mechanical bind that's holding everything back. Let's walk through some of the most common reasons this happens and how you can get back to plowing without needing a tow to the mechanic.
Check Your Controller and Power First
The very first thing I always tell people is to look at the simplest possible cause. Sometimes we get so worried about expensive hydraulic repairs that we overlook a loose plug or a dead controller. If your Fisher plow will not go down, make sure the controller is actually sending a signal. Is the red light on? Does it flicker when you press "Lower"?
If the controller seems dead, check the fuse under your dashboard or in the engine compartment. Fisher systems have a dedicated power wire that can sometimes vibrate loose or get corroded. Also, take a quick look at the grill plugs. These are the big connectors between your truck and the plow. They live a hard life, constantly getting sprayed with road salt and slush. If those pins are green with corrosion or if one is bent, the signal to lower the blade might never reach the plow. A quick spray of contact cleaner and some dielectric grease can work wonders here.
The Infamous S1 Valve
If your motor is humming or clicking but the blade isn't moving, you're likely looking at a hydraulic valve issue. On a Fisher Insta-Act system, the S1 valve is typically responsible for the lowering function. Think of it like a gatekeeper. When you tell the plow to go down, an electrical coil slides a pin in that valve, opening the passage for fluid to flow back into the reservoir so gravity can pull the blade down.
If that S1 valve is stuck or if the coil is burnt out, the "gate" stays closed. You can test this by having someone hold the "down" button while you tap the valve body lightly with a screwdriver handle. Sometimes they just get a little grit in them and need a nudge. If it's truly dead, you'll need to swap the coil or the whole cartridge. It's a messy job, but it's a lot cheaper than a new pump.
Checking the Coil Magnetism
One neat trick to see if your electrical system is actually talking to the valve is the "screwdriver test." Have someone press the down button while you hold a thin screwdriver near the nut on top of the S1 coil. If the coil is getting power, it will become a magnet and pull the screwdriver toward it. If there's no magnetic pull, your problem is electrical—likely a bad ground or a broken wire leading to that specific valve.
Cold Weather and Frozen Fluid
We've all been there—it's ten below zero, and everything on the truck feels like it's made of glass. If your Fisher plow will not go down in extreme cold, there's a good chance you've got some moisture in your hydraulic fluid. Over time, condensation builds up inside the pump reservoir. When the temperature drops, that water turns into tiny ice crystals that can clog the small orifices inside the valves.
If you suspect the fluid is frozen, the best thing you can do is get the truck into a heated garage for a few hours. Once it thaws out and starts working again, you absolutely have to drain the system and put in fresh Fisher Blue hydraulic oil. Don't try to save a few bucks with generic "all-purpose" hydraulic fluid; the genuine blue stuff has anti-icing additives that are worth their weight in gold during a blizzard.
Mechanical Binds and the Lift Chain
Sometimes the problem isn't inside the pump at all. Fisher plows, especially the older MM2 styles, use a lift chain to raise and lower the blade. If that chain is too tight or if it's gotten tangled, it might prevent the lift arm from dropping.
Take a look at the lift ram—the hydraulic cylinder that pulls the chain. If the ram is extended but won't retract, check the packing nut at the top of the cylinder. If it's cranked down way too tight, it can actually squeeze the rod so hard that gravity isn't enough to pull it back down. Also, check for physical obstructions. I've seen cases where a chunk of ice got wedged in the headgear, or the pins that hold the plow to the truck were so rusted and dry that they created enough friction to hold the blade up. A little bit of heavy-duty grease on those pivot points goes a long way.
Understanding the "Float" Mode
It sounds silly, but I've seen plenty of people think their plow is broken when they just aren't using the Float mode correctly. On most Fisher controllers, if you just tap the "down" button, the plow will drop, but it won't stay down with the weight of the blade. To really plow effectively, you have to hold the down button for a second or two until the light on the controller changes (usually it turns green or blinks).
In Float mode, the S1 valve stays open, allowing the blade to follow the contours of the ground. If you're just bumping the button and the blade seems to "stick" or doesn't drop all the way, make sure you're actually engaging that Float function. If the controller refuses to stay in Float, it might be a sign that the controller itself is failing or there's a short in the wiring harness.
Troubleshooting the Solenoid
The motor relay, or solenoid, is that small round canister usually mounted under the hood. While it's most famous for causing the "plow won't go up" problem, a failing solenoid can cause all sorts of weird electrical gremlins. If the solenoid is partially shorted, it might be drawing so much power that the controller resets every time you try to lower the blade.
If you hear a rapid clicking sound when you try to lower the plow, your battery might be low, or the solenoid is struggling to make a clean connection. Fisher pumps pull a massive amount of amps, and if your truck's charging system isn't up to snuff, the electronics will be the first thing to act wonky. Clean your battery terminals and make sure your alternator is actually putting out 14 volts.
Summary of Quick Fixes
When you're stuck in the driveway and your Fisher plow will not go down, run through this mental checklist:
- Wiggle the plugs: Unplug the grill connectors, blow them out, and plug them back in firmly.
- Check the chain: Make sure the lift chain isn't bunched up or caught on the frame.
- Tap the valves: Gently tap the S1 valve on the pump with a screwdriver handle.
- Listen for the click: If you don't hear anything, it's probably a fuse or a dead controller.
- Look for "Float": Ensure you are holding the button long enough to trigger the float light.
Dealing with a plow that won't drop is a pain, but most of the time, it's a simple fix involving a bit of cleaning or a new valve coil. Keeping your fluid fresh and your electrical connections greased will prevent about 90% of these issues from happening in the first place. If you've tried all the basics and it's still stuck in the air, it might be time to pull the valve block apart or call in a professional, but usually, one of these quick checks will get you back to clearing snow in no time.