[GeeMC]

We have a RD 7 ½' MM2 with a fish stick controller we purchased in February that is installed on a 1998 GMC 1500. I am looking for some help in diagnosing a blade movement problem and believe the problem lies in the controller or the isolation module.

This only happens under a load with the blade set all the way to the right, windrowing right. When pressing and holding the left button to shift the snow, the blade will start out moving OK but then stops when it is almost straight on, then moves back to the right all by itself. It doesn’t go back all the way to the right, just about 6-8 inches or so, then resumes it’s travel all the way to the left. Has anyone ever had this happen to them or seen this before? Anyone have any idea where the problem would be located?

The fluid was changed, all the hydraulics are fine and the wiring checks out OK. I checked the charging system and the batteries (2) are operating fine also. This problem doesn’t show up without a load on it which is making it hard to find and it doesn’t do it all the time. We had no problem like this last season.

We have access to another Fish Stick but it is from a MM1 system. Do you think this controller would work on the MM2, just to see if the problem is in the controller?



Thanks for your help,

Bruce

 

[BRL]

I'll take a stab that the "load" you are putting the plow under is too much to move it to the left. So it moves til it becomes too much, then possibly the crossover relief kicks in, and then the load becomes light enough to move again for some reason & the plow can then keep moving to the left. Or there is some dirt in one of the valves LOL. Good luck with it.

 

[GeeMC]

BRL, we thought along those lines too but it can happen when there is no snow on the blade also, just scraping the bare pavement. Maybe I should have defined load as; with the blade off the ground it doesn't happen at all. And it may be a stuck relief or switching valve, still investigating.

Thanks,

Bruce

 

[Arc Burn]

The Fishstick is interchangable between MM1 and MM2's though it sounds like a cross over valve problem.

 

[GeeMC]

Ok, thanks Arc Burn. I'll check that out next.

Bruce

 

[GeeMC]

OK, there is nothing in the manuals on a crossover valve or crossover relief. They do show a bypass check valve. Here is a link to the diagram and parts list. http://www.fisherplows.com/pdf/21993_041503.pdf page 6 and 7.

Anyone got any clues you can send this way?

Thanks,

Bruce

 

[Arc Burn]

It's actually called a Cushion Valve,you can pull that assembly and check the O-rings,also check the spring to be sure it isn't broke(unlikely)when you put them back,screw them all the way till the spring bottoms out and then back off 1.25 - 1.50 turns.
I'm assuming you tryed the other Fishstick?

 

[GeeMC]

Ha...just noticed I never posted the fix for this thread. The problem was in the fish stick. I brought the truck back to the dealer and he messed with the wiring were it came out of the grill. He found nothing wrong and put on another fish stick...problem solved. :grinz Touchy things I say!

All covered under warranty too.

 

[BWhite]

Was the new stick a warranty replacement or did it cost you ? How much are replacements ?

 

[GeeMC]

The new one came under warranty. We even blew it again earlier this year. They covered that one too with some fast talking. I had a long talk with my weight lifting driver (son) about taking his anger management out on my controller :rolling :haha

New ones are about 250 bucks!

Bruce

 

[BWhite]

$250 is good enough incentive to take it easy on the thing !